Veselinova, Ljuba. Suppletion in Verb Paradigms – Bits and Pieces of the Puzzle. Amsterdam: John Benjamins Publishing Company, 2006.
A PhD thesis on suppletion from 2003, Stockholm University.
:-)
Previously released scans from bentstavanger:
Osthoff, Hermann. Vom Suppletivwesen der indogermanischen Sprachen.
Samuels, M.L. Linguistic Evolution with Special Reference to English.