@article{CM_1974__29_3_223_0,
     author = {Stong, R. E.},
     title = {Semi-characteristics and free group actions},
     journal = {Compositio Mathematica},
     pages = {223--248},
     publisher = {Noordhoff International Publishing},
     volume = {29},
     number = {3},
     year = {1974},
     mrnumber = {377943},
     zbl = {0294.57021},
     language = {en},
     url = {http://archive.numdam.org/item/CM_1974__29_3_223_0/}
}