Matematyk.

Category theory : applications to algebra, logic and topology proceedings of the International Conference held at Gummersbach, july 6-10, 1981 / ed. by K. H. Kamps, D. Pumplün, and W. Tholen. - Berlin, 1982. (Fachbereich Mathematik un Informatik Fernuniversität - Gesamthochschule - Hagen, FRG)

LCA online

http://www.math.yorku.ca/Who/Faculty/Tholen/menu.html