Californians for Electoral ReformSupports AV as well as PR
How Proportional Representation Elections Work From the US organization fairvote.org
Candidate Selection and List PR by Mike Ossipoff
Allocation Formulas for Party List PR by Mike Ossipoff. This is also relevant to the allocation of House Representatives between States in the US
District systems for PR by Mike Ossipoff
Sainte-Lague's exchange property by Mike Ossipoff
A simple method of implementing Single Transferable Vote by Mike Ossipoff