Theory of rankings
Mark Hopkins description of various systems
and
Bihl's reply
Chi-square based systems
Masseys system based on chi-square fitting
Mike Zenors description of chi-square fitting.
Elo based systems
Sauceda Rating System
US Chess Federation's rating system
Roy Jones's description of Chess rating systems
E-based rating systems
Massey description of Potemkins system
Potemkins description