%0 Journal Article %A Stong, R. E. %T Semi-characteristics and free group actions %J Compositio Mathematica %D 1974 %P 223-248 %V 29 %N 3 %I Noordhoff International Publishing %U http://archive.numdam.org/item/CM_1974__29_3_223_0/ %G en %F CM_1974__29_3_223_0