Surya Siddhanta / Book / Encyclopedia / Comparing

http://en.wikipedia.org/wiki/Surya_Siddhanta
http://www.wilbourhall.org/pdfs/suryaEnglish.pdf
http://www.nationmaster.com/encyclopedia/Surya-Siddhanta
http://www.math.nus.edu.sg/aslaksen/projects/dc-urops.pdf