References
10 – first dance - http://www.historyworld.net/wrldhis/PlainTextHistories.asp?ParagraphID=ihf
https://en.wikipedia.org/wiki/Bhimbetka_rock_shelters
https://en.wikipedia.org/wiki/History_of_dance

9 – zodiac signs - http://www.historyworld.net/wrldhis/PlainTextHistories.asp?historyid=ac32
https://www.astrologers.com/about/history

8 – invisible shadow - http://www.sciencefocus.com/qa/if-you-could-make-yourself-invisible-would-you-still-have-shadow
https://www.quora.com/If-you-were-invisible-would-you-have-a-shadow

7 – worst computer virus - http://www.hongkiat.com/blog/famous-malicious-computer-viruses/
http://www.bbc.com/news/10095957

6 – American football - https://www.quora.com/Why-is-American-football-called-football-%E2%80%94-as-most-of-the-sport-involves-using-your-hands
http://sports.stackexchange.com/questions/341/why-is-american-football-called-football
http://www.primermagazine.com/2009/field-manual/know-it-all-why-is-american-football-called-%E2%80%9Cfootball%E2%80%9D

5 – albino animals - http://files.dnr.state.mn.us/mcvmagazine/young_naturalists/young-naturalists-article/albino_animals/albino_animals.pdf
https://www.scientificamerican.com/article/killing-albinos-tanzania-albinism/

4 – clean as a whistle - http://www.word-detective.com/2010/03/whistle-clean-as-a/
http://justinletourneau.blogspot.com.au/2012/03/clean-as-whistle.html

3 – computers and internet -  http://www.computerhope.com/issues/ch000984.htm
http://www.history.com/news/ask-history/who-invented-the-internet
https://en.wikipedia.org/wiki/Difference_engine

2 – turbulence - http://www.telegraph.co.uk/travel/travel-truths/What-causes-turbulence-and-is-it-dangerous/
http://www.travelandleisure.com/articles/what-is-turbulence

1 – rare object - https://en.wikipedia.org/wiki/Painite
http://www.aol.com/photos/rarest-items-in-the-world/#slide=986366#fullscreen
https://answers.yahoo.com/question/index?qid=20100212190754AAl0aG1