@article{GDZPPN002057174,
title = {Essential and inessential complexes.},
journal = {Commentarii mathematici Helvetici},
volume = {33},
year = {1959},
pages = {70-80},
zbl = {0178.26201},
url = {http://dml.mathdoc.fr/item/GDZPPN002057174}
}
Bertsein, Israel. Essential and inessential complexes.. Commentarii mathematici Helvetici, Tome 33 (1959) pp. 70-80. http://gdmltest.u-ga.fr/item/GDZPPN002057174/