(2004) Letters in Mathematical Physics : a journal for the rapid dissemination of short contributions in the field of mathematical physics — Vol. 69, p. 147-156 (2004)
Bertelson, M. (2004). Topological invariants for discrete group actions. Letters in Mathematical Physics : a journal for the rapid dissemination of short contributions in the field of mathematical physics, 69, 147-156. https://doi.org/10.1007/s11005-004-9188-x (Original work published 2004)