@article{1255630887, author = {Heller, Alex}, title = {Homotopy invariants of chain complexes}, journal = {Illinois J. Math.}, volume = {5}, number = {1}, year = {1961}, pages = { 420-424}, language = {en}, url = {http://dml.mathdoc.fr/item/1255630887} }
Heller, Alex. Homotopy invariants of chain complexes. Illinois J. Math., Tome 5 (1961) no. 1, pp. 420-424. http://gdmltest.u-ga.fr/item/1255630887/