K. Gawędzki, "Topological Actions in Two-Dimensional Quantum Field Theories", IHES preprint
of an article (by the same title) published in "Nonperturbative Quantum Field Theory", (G. 't Hooft, A. Jaffe,
G. Mack, P. Mitter and R. Stora, eds.), Plenum Press, 1988, pp.101-141.