Brahmagupta

https://en.wikipedia.org/wiki/Brahmagupta
http://www.storyofmathematics.com/indian_brahmagupta.html
http://www.thefamouspeople.com/profiles/brahmagupta-6842.php
http://www.math.wsu.edu/mathlessons/html/zero/zeronumber.html
http://www-groups.dcs.st-and.ac.uk/~history/Biographies/Brahmagupta.html
http://www.livingmath.net/MathSites/C1U2MedievalTimes/AryabhataBrahmagupta/tabid/422/Default.aspx

Video
https://www.youtube.com/watch?v=PcljF2TTz4k