Reference sites including:
sdcc14.ucsd.edu/~fillmore/blurbs/Pythagoras/pyth.html
www.graphcomp.com/home/bfree/arch/domes.html
antwrp.gsfc.nasa.gov/apod/ap960831.html
www.geom.umn.edu/~demo5337/Group3/hist.html
www.best.com/~`xah/SpecialPlaneCurves_dir/Ellipse_dir/ellipse.html
www.swan.ac.uk/compsci/ResearchGroups/TheoryGroups/AlgmethFolder/DSTFolder/HistoryOfTables/Plimpton/Plimpton.html