Chapter 19
www.wordsmith.org/~anu/java/spirograph.html
http://csdt.rpi.edu/african/African_Fractals/
classes.yale.edu/fractals/index.html
http://www.math.smith.edu/phyllo/index.html
http://www.maths.surrey.ac.uk/hosted-sites/R.Knott/Fibonacci/fib.html