references

 

paul bourke, mental health research institute, victoria, australia
"http://www.mhri.edu.au/~pdb/geometry/steiner.html"

 

adam coffman, university of chicago
"http://www.math.uchicago.edu/~adamc/steinersurface.html"

 

the geometry center
"http://www.geom.umn.edu/zoo/toptype/pplane/roman/"

 

john j o'connor and edmund f robertson, university of st andrews, st andrews, scotland
"http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Steiner.html"