This Week's Finds in Mathematical Physics (Week 214) by John Baez.
An installment of John's blog relevant to the link above.
Klein's Quartic Curve by Greg Egan
 
The Beauty of Klein's Quartic by John Baez
Klein's Quartic Equation by Greg Egan  
 
Platonic tilings of Riemann surfaces
This site has many illustrations and links to other related sites not included here. It provides some background relevant to the Platonic surfaces assignment.
On the Order-Seven Transformation of Elliptic Functions by Felix Klein (46 pages)
English translation of an 1878 paper by Klein relevant to the {3,7} tesselation. (The first page of this paper is blank; go to the second page.) 
 
Infinite Regular Polyhedra
This site has picture of many infinite Platonic surfaces and links to other similar ones with more of them. The one shown here has Schläfli symbol {4,6}.
Combinatorial Tiling Theory and Delaney-Dress Symbols
"The study of tilings has a long history, but it was only in the 1980's that a finite symbol was found to uniquely encode both the topology and symmetry of an infinite periodic tiling."