@article{GDZPPN002057549, title = {Homotopy mod. C of Spaces of Category 2.}, journal = {Commentarii mathematici Helvetici}, volume = {35}, year = {1961}, pages = {9-14}, zbl = {0095.16901}, url = {http://dml.mathdoc.fr/item/GDZPPN002057549} }
Berstein, Israel. Homotopy mod. C of Spaces of Category 2.. Commentarii mathematici Helvetici, Tome 35 (1961) pp. 9-14. http://gdmltest.u-ga.fr/item/GDZPPN002057549/