http://britton.disted.camosun.bc.ca/houle/Escher_II_Infinite_Reflection_Detail.html
http://britton.disted.camosun.bc.ca/houle/Escher_II_Infinite_Reflection.html
http://britton.disted.camosun.bc.ca/houle/Escher_I_Double_Reflection.html


Kelly M Houle, 1998