@article{GDZPPN00241225X,
title = {Groupoid Operations and Fibre-Homotopy Equivalence. I.},
journal = {Mathematische Zeitschrift},
volume = {135},
year = {1973},
pages = {207-234},
zbl = {0253.55008},
url = {http://dml.mathdoc.fr/item/GDZPPN00241225X}
}
Heath, Philip R. Groupoid Operations and Fibre-Homotopy Equivalence. I.. Mathematische Zeitschrift, Tome 135 (1973) pp. 207-234. http://gdmltest.u-ga.fr/item/GDZPPN00241225X/