Kalimat Bijak yang Harus Didengar Anak di Seluruh Dunia

Anak adalah aset luar biasa yang dititipkan oleh Tuhan kepada kita. Memiliki anak sama dengan memiliki tanggung jawab yang besar. Anda bertanggung jawab penuh padanya, bagaimana cara mendidik mereka, apa saja yang mereka butuhkan untuk bertumbuh, serta curahan kasih sayang Anda sangat mereka butuhkan.

Selain itu, Anda juga bertanggung jawab untuk membimbing mereka. Karena mengasuh anak tidaklah mudah, kadang Anda harus memilah-milah kata yang pantas untuk diucapkan. Apalagi jika anak Anda masih kecil. Seperti yang dilansir dari babble.com, berikut words of wisdom yang harus didengar semua anak di dunia.


Jeans never go out of style

Katakan pada mereka bahwa tidak selamanya menggunakan jeans itu keren. Pakailah pakaian sesuai seragam sekolah dan jangan khawatir tentang mode. Hal ini mengajarkan kepada anak-anak kita untuk mematuhi peraturan yang ada, meskipun banyak godaan.


Semua ada waktunya

Kesabaran adalah sebuah kebajikan. Tanamkan pada anak Anda buah-buah kesabaran. Tidak semuanya yang mereka inginkan dapat terkabul sekarang juga. Seperti kalimat klise "Semua akan indah pada waktu-Nya", tetapi memang janji Tuhan tak pernah ingkar.


Keep on, keepin' on

Hidup tak selamanya mudah. Pasti ada kerikil-kerikil yang menghambat jalan anak Anda kelak. Ajari mereka semangat pantang menyerah. Kerja keras dan ketekunan yang akan mengantar mereka pada gerbang kesuksesan.


Kamu tak pernah sendirian

Iya, apapun yang terjadi, mereka tak akan pernah sendirian. Anda, suami Anda, semua anggota keluarga, ataupun sahabat mereka kelak pasti akan selalu ada. Ajari mereka mandiri, apapun yang bisa mereka lakukan sendiri, lakukan. Tetapi jika mereka merasa gagal atau mempunyai masalah, ingatkan bahwa mereka tak pernah sendirian.


Taklukkan dunia

"Dunia ada di tanganmu, nak", biarkan mereka belajar apa saja. Kembangkan potensi mereka. Ketidaknyamanan dalam melakukan sesuatu membuat mereka tidak berkembang. "Tak ada noda, tak belajar," begitu kata salah satu iklan.

Meskipun memiliki anak adalah tanggung jawab yang besar, jangan terlalu dijadikan beban. Orang tua merupakan salah satu jalan anak untuk menuju sukses. 


Sumber :
vemale.com

Orang-orang yang Ditemukan Mati Setelah Bertahun-tahun

Individualisme, asosial adalah efek yang timbul ketika kapitalis melunturkan nilai-nilai gotong-royong. Perlahan-lahan penyakit ini semakin berkembang di negara-negara timur, termasuk Indonesia, yang sebenarnya menganut paham kebersamaan.

Sekarang kita mungkin baru dalam tahap tak peduli terhadap hidup bertetangga, tak tahu ketika ada pendatang baru yang menutup diri. Atau misalnya tak acuh melihat orang lain kesusahan. Dan layaknya tumor, apakah penyakit individualisme harus menunggu beberapa tahun ke depan sampai dampak buruknya jelas terasa?

Mungkin contoh-contoh berikut bisa membuka mata kita, bahwa kesendirian, ketakpedulian hanya meninggalkan kenangan pedih. Inilah orang-orang yang mati dalam sunyi, dan baru disadari banyak orang bertahun-tahun sesudahnya.


1. Kroasia - Mati di depan TV 42 tahun

Hedviga Golik (lahir 1924) hidup sendiri dalam flat (apartemen). Tak  banyak laporan tentang kehidupan wanita Kroasia ini. Tetangganya hanya mengingat terakhir kali melihat Golik tahun 1966 (berarti saat umur Golik 42 tahun). Setelah itu tak ada lagi kabarnya. Para tetangga menduga ia sudah pindah.

Bertahun-tahun kemudian (mungkin 2007 atau 2008) barulah muncul laporan orang hilang di kantor polisi setempat. Maka aparat pun mendatangi flat Golik, mendobraknya, dan menemukan jasad wanita ini duduk di depan televisi hitam putihnya. Tubuhnya sudah rusak, tulang tengkoraknya terlihat jelas.

Dari kali terakhir terlihat tetangganya, berarti Golik telah meninggal dan baru diketahui 42 tahun setelahnya. Tragis, hanya kursi, tv hitam putih, dan secangkir teh menemani sang mumi selama puluhan tahun.



2. Prancis - Mati masih ber-piyama

Tak selalu apartemen yang menyekat kehidupan pribadi sehingga sangat individualis. Tinggal di rumah pun kalau tak ada interaksi sosial juga gawat. Seorang pria yang tinggal di sebuah rumah di Lille, Prancis ditemukan mati masih mengenakan piyama setelah 15 tahun kemudian oleh kepolisian setempat.

Banyak orang mengira rumah ini sudah kosong. Tampaknya pria asli Spanyol ini tak punya kenalan saat tinggal di Lille. Waktu kematian diduga tahun 1996, terlihat dari surat-surat yang masih tertutup merujuk tahun tersebut.



3. Prancis - Ditemukan setelah 8 tahun gantung diri

Sebuah Apartemen di paris dikejutkan penemuan mayat gantung diri yang sudah berusia delapan tahun berada di apartemen tersebut. Usia pria ini sekitar 40 tahun, terakhir kabarnya mengajukan keluhan pekerja terhadap pemecatannya di tahun 2005.

Dia telah memutuskan hubungan dengan keluarganya dan kabar dari tetangga percaya bahwa ia telah kembali ke Kamboja. Apartemennya akhirnya dijual setelah ia tidak mampu untuk  pembayaran hipotek dan untuk menutupi biaya bangunan.

Seorang sumber polisi mengatakan pemilik baru menemukan tubuh pria asli Kamboja ini tergantung di tali saat tiba untuk memeriksa apartemen dan masuk dengan bantuan tukang kunci.



4. Australia - Ditemukan setelah 8 tahun

Seorang wanita tua (87 tahun) yang hidup sendirian di rumahnya ditemukan sudah meninggal setelah 8 tahun oleh kepolisian New South Wales, Australia pada tahun 2011. Bagaimana mungkin rumah itu dibiarkan tak terurus sekian tahun? Tampaknya listrik dan air sudah diputus sejak lama. Namun, Departemen Sosial tetap memberi tunjangan ke rekeningnya. Para tetangga melaporkan tak pernah melihat wanita itu dan mengiranya sedang liburan.

Penemuan mayat ini dilakukan setelah polisi menerima laporan dari iparnya yang tak mendengar kabar setelah bertahun-tahun. Sangat disayangkan, mengapa menunggu 8 tahun baru melapor polisi?

Menurut keterangan, wanita tua ini dan iparnya bertengkar hebat di tahun 2003, dan setelah itu mereka berdua perang dingin. Tragis, sebuah pertengkaran yang panjang menuai hasil menyedihkan.

5. Jerman - Mati di tempat tidur 7 tahun

Ini mungkin kisah paling tragis hidup kesepian dalam sebuah negara yang sangat maju, Jerman. Di tahun 2007 polisi menemukan seorang pria berusia 59 tahun mati terbaring di tempat tidurnya. Waktu kematian diduga 30 November 2000 sesuai surat bertanggal tersebut yang datang dari kantor Departemen Sosial (welfare office).

Apartemen pria ini di gedung yang meliputi perkantoran. Mengingat lingkungan yang cukup ramai tersebut, seharusnya bau mayat busuk tercium dengan mudah. Nyatanya tidak ada orang yang 'ngeh' selama bertahun-tahun. Tambah menyedihkan, tak ada orang yang merasa kehilangan kakek/ayah/teman dan artinya pria ini benar-benar hidup sendirian.

"Tak ada yang kehilangan pria ini. Tak pernah ada laporan kehilangan," ucap polisi setempat. Sungguh mengenaskan, begitu mudahnya melupakan orang.

------

Masih banyak laporan lain yang bisa ditemukan dari berita-berita di internet, kebanyakan memang dari negara-negara yang disebut maju peradabannya, maju secara teknologi, namun mundur dalam kehidupan sosial. Ironis?

Indonesia dan negara-negara timur yang masih menjunjung budaya kebersamaan belum terlampau parah, mungkin. Tapi indikasi ke arah sana bisa saja dipercepat. Seperti misalnya berita di bulan September 2013 tentang penemuan mayat Adi Prahara Mahdisa setelah membusuk di kamar kosnya di kawasan Kebon Kacang 9 No 35, Jakarta Pusat. Masih hitungan hari, tepatnya dua hari. Bagaimanapun sungguh menyedihkan, kabar kehilangan diterima polisi berkat laporan teman kerjanya.

Sumber:
oddee.com
liputan6

10 Easy Things That Will Make You Happier, Backed By Science

Happiness is so interesting, because we all have different ideas about what it is and how to get it. So naturally we are obsessed with it.. I would love to be happier, as I’m sure most people would, so I thought it would be interesting to find some ways to become a happier person that are actually backed up by science. Here are ten of the best ones I found.

1. Exercise more – 7 minutes might be enough

You might have seen some talk recently about the scientific 7 minute workout mentioned in The New York Times. So if you thought exercise was something you didn’t have time for, maybe you can fit it in after all.

Exercise has such a profound effect on our happiness and well-being that it’s actually been proven to be an effective strategy for overcoming depression. In a study cited in Shawn Achor’s book, The Happiness Advantage, three groups of patients treated their depression with exercise. The results of this study really surprised me. Although all three groups experienced similar improvements in their happiness levels to begin with, the follow up assessments proved to be radically different:

The groups were then tested six months later to assess their relapse rate. Of those who had taken the medication alone, 38 percent had slipped back into depression. Those in the combination group were doing only slightly better, with a 31 percent relapse rate. The biggest shock, though, came from the exercise group: Their relapse rate was only 9 percent!

You don’t have to be depressed to gain benefit from exercise, though. It can help you to relax, increase your brain power and even improve your body image, even if you don’t lose any weight.

A study in the Journal of Health Psychology found that people who exercised felt better about their bodies, even when they saw no physical changes:

Body weight, shape and body image were assessed in 16 males and 18 females before and after both 6 × 40 mins exercise and 6 × 40 mins reading. Over both conditions, body weight and shape did not change. Various aspects of body image, however, improved after exercise compared to before.

We’ve explored exercise in depth before, and looked at what it does to our brains, such as releasing proteins and endorphins that make us feel happier, as you can see in the image below.

2. Sleep more – you’ll be less sensitive to negative emotions

We know that sleep helps our bodies to recover from the day and repair themselves, and that it helps us focus and be more productive. It turns out, it’s also important for our happiness.

In NutureShock, Po Bronson and Ashley Merryman explain how sleep affects our positivity:

Negative stimuli get processed by the amygdala; positive or neutral memories gets processed by the hippocampus. Sleep deprivation hits the hippocampus harder than the amygdala. The result is that sleep-deprived people fail to recall pleasant memories, yet recall gloomy memories just fine.

In one experiment by Walker, sleep-deprived college students tried to memorize a list of words. They could remember 81% of the words with a negative connotation, like “cancer.” But they could remember only 31% of the words with a positive or neutral connotation, like “sunshine” or “basket.”

The BPS Research Digest explores another study that proves sleep affects our sensitivity to negative emotions. Using a facial recognition task over the course of a day, the researchers studied how sensitive participants were to positive and negative emotions. Those who worked through the afternoon without taking a nap became more sensitive late in the day to negative emotions like fear and anger.

Using a face recognition task, here we demonstrate an amplified reactivity to anger and fear emotions across the day, without sleep. However, an intervening nap blocked and even reversed this negative emotional reactivity to anger and fear while conversely enhancing ratings of positive (happy) expressions.

Of course, how well (and how long) you sleep will probably affect how you feel when you wake up, which can make a difference to your whole day. Especially this graph showing how your brain activity decreases is a great insight about how important enough sleep is for productivity and happiness:

Another study tested how employees’ moods when they started work in the morning affected their work day.

Researchers found that employees’ moods when they clocked in tended to affect how they felt the rest of the day. Early mood was linked to their perceptions of customers and to how they reacted to customers’ moods.

And most importantly to managers, employee mood had a clear impact on performance, including both how much work employees did and how well they did it.

Sleep is another topic we’ve looked into before, exploring how much sleep we really need to be productive.

3. Move closer to work – a short commute is worth more than a big house

Our commute to the office can have a surprisingly powerful impact on our happiness. The fact that we tend to do this twice a day, five days a week, makes it unsurprising that its effect would build up over time and make us less and less happy.

According to The Art of Manliness, having a long commute is something we often fail to realize will affect us so dramatically:

… while many voluntary conditions don’t affect our happiness in the long term because we acclimate to them, people never get accustomed to their daily slog to work because sometimes the traffic is awful and sometimes it’s not. Or as Harvard psychologist Daniel Gilbert put it, “Driving in traffic is a different kind of hell every day.”

We tend to try to compensate for this by having a bigger house or a better job, but these compensations just don’t work:

Two Swiss economists who studied the effect of commuting on happiness found that such factors could not make up for the misery created by a long commute.

4. Spend time with friends and family – don’t regret it on your deathbed

Staying in touch with friends and family is one of the top five regrets of the dying. If you want more evidence that it’s beneficial for you, I’ve found some research that proves it can make you happier right now.

Social time is highly valuable when it comes to improving our happiness, even for introverts. Several studies have found that time spent with friends and family makes a big difference to how happy we feel, generally.

I love the way Harvard happiness expert Daniel Gilbert explains it:

We are happy when we have family, we are happy when we have friends and almost all the other things we think make us happy are actually just ways of getting more family and friends.

George Vaillant is the director of a 72-year study of the lives of 268 men.

In an interview in the March 2008 newsletter to the Grant Study subjects, Vaillant was asked, “What have you learned from the Grant Study men?” Vaillant’s response: “That the only thing that really matters in life are your relationships to other people.”

He shared insights of the study with Joshua Wolf Shenk at The Atlantic on how the men’s social connections made a difference to their overall happiness:

The men’s relationships at age 47, he found, predicted late-life adjustment better than any other variable, except defenses. Good sibling relationships seem especially powerful: 93 percent of the men who were thriving at age 65 had been close to a brother or sister when younger.

In fact, a study published in the Journal of Socio-Economics states than your relationships are worth more than $100,000:

Using the British Household Panel Survey, I find that an increase in the level of social involvements is worth up to an extra £85,000 a year in terms of life satisfaction. Actual changes in income, on the other hand, buy very little happiness.

I think that last line is especially fascinating: Actual changes in income, on the other hand, buy very little happiness. So we could increase our annual income by hundreds of thousands of dollars and still not be as happy as if we increased the strength of our social relationships.

The Terman study, which is covered in The Longevity Project, found that relationships and how we help others were important factors in living long, happy lives:

We figured that if a Terman participant sincerely felt that he or she had friends and relatives to count on when having a hard time then that person would be healthier. Those who felt very loved and cared for, we predicted, would live the longest.

Surprise: our prediction was wrong… Beyond social network size, the clearest benefit of social relationships came from helping others. Those who helped their friends and neighbors, advising and caring for others, tended to live to old age.

5. Go outside – happiness is maximized at 13.9°C

In The Happiness Advantage, Shawn Achor recommends spending time in the fresh air to improve your happiness:

Making time to go outside on a nice day also delivers a huge advantage; one study found that spending 20 minutes outside in good weather not only boosted positive mood, but broadened thinking and improved working memory…

This is pretty good news for those of us who are worried about fitting new habits into our already-busy schedules. Twenty minutes is a short enough time to spend outside that you could fit it into your commute or even your lunch break.

A UK study from the University of Sussex also found that being outdoors made people happier:

Being outdoors, near the sea, on a warm, sunny weekend afternoon is the perfect spot for most. In fact, participants were found to be substantially happier outdoors in all natural environments than they were in urban environments.

The American Meteorological Society published research in 2011 that found current temperature has a bigger effect on our happiness than variables like wind speed and humidity, or even the average temperature over the course of a day. It also found that happiness is maximized at 13.9°C, so keep an eye on the weather forecast before heading outside for your 20 minutes of fresh air.

6. Help others – 100 hours a year is the magical number

One of the most counterintuitive pieces of advice I found is that to make yourself feel happier, you should help others. In fact, 100 hours per year (or two hours per week) is the optimal time we should dedicate to helping others in order to enrich our lives.

If we go back to Shawn Achor’s book again, he says this about helping others:

…when researchers interviewed more than 150 people about their recent purchases, they found that money spent on activities—such as concerts and group dinners out—brought far more pleasure than material purchases like shoes, televisions, or expensive watches. Spending money on other people, called “prosocial spending,” also boosts happiness.

The Journal of Happiness Studies published a study that explored this very topic:

Participants recalled a previous purchase made for either themselves or someone else and then reported their happiness. Afterward, participants chose whether to spend a monetary windfall on themselves or someone else. Participants assigned to recall a purchase made for someone else reported feeling significantly happier immediately after this recollection; most importantly, the happier participants felt, the more likely they were to choose to spend a windfall on someone else in the near future.

So spending money on other people makes us happier than buying stuff for ourselves. What about spending our time on other people? A study of volunteering in Germany explored how volunteers were affected when their opportunities to help others were taken away:

 Shortly after the fall of the Berlin Wall but before the German reunion, the first wave of data of the GSOEP was collected in East Germany. Volunteering was still widespread. Due to the shock of the reunion, a large portion of the infrastructure of volunteering (e.g. sports clubs associated with firms) collapsed and people randomly lost their opportunities for volunteering. Based on a comparison of the change in subjective well-being of these people and of people from the control group who had no change in their volunteer status, the hypothesis is supported that volunteering is rewarding in terms of higher life satisfaction.

In his book Flourish: A Visionary New Understanding of Happiness and Well-being, University of Pennsylvania professor Martin Seligman explains that helping others can improve our own lives:

…we scientists have found that doing a kindness produces the single most reliable momentary increase in well-being of any exercise we have tested.

7. Practice smiling – it can alleviate pain

Smiling itself can make us feel better, but it’s more effective when we back it up with positive thoughts, according to this study:

A new study led by a Michigan State University business scholar suggests customer-service workers who fake smile throughout the day worsen their mood and withdraw from work, affecting productivity. But workers who smile as a result of cultivating positive thoughts – such as a tropical vacation or a child’s recital – improve their mood and withdraw less.

Of course it’s important to practice “real smiles” where you use your eye sockets. It’s very easy to spot the difference:

According to PsyBlog, smiling can improve our attention and help us perform better on cognitive tasks:

Smiling makes us feel good which also increases our attentional flexibility and our ability to think holistically. When this idea was tested by Johnson et al. (2010), the results showed that participants who smiled performed better on attentional tasks which required seeing the whole forest rather than just the trees.

A smile is also a good way to alleviate some of the pain we feel in troubling circumstances:

Smiling is one way to reduce the distress caused by an upsetting situation. Psychologists call this the facial feedback hypothesis. Even forcing a smile when we don’t feel like it is enough to lift our mood slightly (this is one example of embodied cognition).

One of our previous posts goes into even more detail about the science of smiling.

8. Plan a trip – but don’t take one

As opposed to actually taking a holiday, it seems that planning a vacation or just a break from work can improve our happiness. A study published in the journal, Applied Research in Quality of Lifeshowed that the highest spike in happiness came during the planning stage of a vacation as employees enjoyed the sense of anticipation:

In the study, the effect of vacation anticipation boosted happiness for eight weeks.

After the vacation, happiness quickly dropped back to baseline levels for most people.

Shawn Achor has some info for us on this point, as well:

One study found that people who just thought about watching their favorite movie actually raised their endorphin levels by 27 percent.

If you can’t take the time for a vacation right now, or even a night out with friends, put something on the calendar—even if it’s a month or a year down the road. Then whenever you need a boost of happiness, remind yourself about it.

9. Meditate – rewire your brain for happiness

Meditation is often touted as an important habit for improving focus, clarity and attention span, as well as helping to keep you calm. It turns out it’s also useful for improving your happiness:

In one study, a research team from Massachusetts General Hospital looked at the brain scans of 16 people before and after they participated in an eight-week course in mindfulness meditation. The study, published in the January issue of Psychiatry Research: Neuroimaging, concluded that after completing the course, parts of the participants’ brains associated with compassion and self-awareness grew, and parts associated with stress shrank.

Meditation literally clears your mind and calms you down, it’s been often proven to be the single most effective way to live a happier live. I believe that this graphic explains it the best:

According to Shawn Achor, meditation can actually make you happier long-term:

Studies show that in the minutes right after meditating, we experience feelings of calm and contentment, as well as heightened awareness and empathy. And, research even shows that regular meditation can permanently rewire the brain to raise levels of happiness.

The fact that we can actually alter our brain structure through mediation is most surprising to me and somewhat reassuring that however we feel and think today isn’t permanent.

10. Practice gratitude – increase both happiness and life satisfaction

This is a seemingly simple strategy, but I’ve personally found it to make a huge difference to my outlook. There are lots of ways to practice gratitude, from keeping a journal of things you’re grateful for, sharing three good things that happen each day with a friend or your partner, and going out of your way to show gratitude when others help you.

In an experiment where some participants took note of things they were grateful for each day, their moods were improved just from this simple practice:

The gratitude-outlook groups exhibited heightened well-being across several, though not all, of the outcome measures across the 3 studies, relative to the comparison groups. The effect on positive affect appeared to be the most robust finding. Results suggest that a conscious focus on blessings may have emotional and interpersonal benefits.

The Journal of Happiness studies published a study that used letters of gratitude to test how being grateful can affect our levels of happiness:

Participants included 219 men and women who wrote three letters of gratitude over a 3 week period.

Results indicated that writing letters of gratitude increased participants’ happiness and life satisfaction, while decreasing depressive symptoms.

Quick last fact: Getting older will make yourself happier

As a final point, it’s interesting to note that as we get older, particularly past middle age, we tend to grow happier naturally. There’s still some debate over why this happens, but scientists have got a few ideas:

Researchers, including the authors, have found that older people shown pictures of faces or situations tend to focus on and remember the happier ones more and the negative ones less.

Other studies have discovered that as people age, they seek out situations that will lift their moods — for instance, pruning social circles of friends or acquaintances who might bring them down. Still other work finds that older adults learn to let go of loss and disappointment over unachieved goals, and hew their goals toward greater wellbeing.

So if you thought being old would make you miserable, rest assured that it’s likely you’ll develop a more positive outlook than you probably have now.

Want to chat about this article? Leave a comment below or send me an email with your thoughts.

Oh and before I forget, we’ve recently launched the new Buffer for Business. Take a look, it’s the most powerful Buffer yet to help you better manage your social media everywhere.

Photo credit: Spencer Finnley

Source of this article: Buffer

http://www.themindunleashed.org/

Internet Membuat Kita Cepat Jadi Pelupa

Sebuah penelitian psikolog mengungkapkan dampak buruk internet, yakni "efek Google" membuat manusia modern punya memori lebih pendek.

Pernahkah Anda dihadapkan pada kasus kemudian lupa jawabannya, lalu teman Anda atau mungkin pikiran Anda sendiri memberi solusi cepat: cari saja di Google. Begitulah, ketergantungan manusia modern pada Internet untuk mengecek sebuah fakta dan informasi dasar lainnya telah mengakibatkan tingkat pertumbuhan lupa sangat cepat.

 

Foto: indonesiarayanews.com

 

 

Psikolog Daniel Wegner dan Adrian Ward dari Universitas Harvard memperingatkan bahwa individu yang percaya fakta mengesankan mereka disimpan secara online jauh lebih buruk dalam ingatan.

"Penelitian kami menunjukkan bahwa kita memperlakukan Internet seperti mitra memori transaktif manusia atau orang, di mana kita biasanya berbagi tentang informasi pribadi," kata Wegner.

Timnya menemukan bahwa banyak orang sekarang melihat mesin pencari Internet seperti Google dan lainnya sebagai perpanjangan kecerdasan mereka sendiri daripada alat terpisah.

"Internet bukan hanya mengambil tempat orang lain sebagai sumber eksternal memori, tapi juga dari kemampuan kognitif kita sendiri," katanya. "Kami menyebutnya efek Google."

Dalam serangkaian tes, peneliti menemukan bahwa peserta lebih cenderung untuk mengingat informasi jika mereka percaya telah terhapus. Mereka yang berpikir memori itu disimpan di komputer akan lebih pelupa, bahkan jika mereka secara eksplisit diminta untuk menyimpan informasi itu dalam pikirannya. "Kita sekarang jauh lebih buruk dalam mengingat fakta-fakta yang kita tahu yang tersedia secara online," katanya.

Hasil penelitan Wegner dan Ward diterbitkan dalam jurnal Scientific American.

Sumber:
tempo