Gordon, Theodore J. Singh, Parmanand "The So-called Fibonacci numbers in ancient and medieval India" HISTORIA MATHEMATICA 12 (1985) 229-244: http://tjure.sfs.uni-tuebingen.de/files/Kursmaterialien/Gerdemann/sdarticle.pdf Ron Knott's multimedia web site on the Fibonacci numbers: http://www.maths.surrey.ac.uk/hosted- sites/R.Knott/Fibonacci/fibnat.html