@article{GDZPPN002022451,
title = {Medial Topological Groupoids.},
journal = {Aequationes mathematicae},
volume = {1},
year = {1968},
pages = {217-234},
zbl = {0164.33604},
url = {http://dml.mathdoc.fr/item/GDZPPN002022451}
}
Sigman, Kermit. Medial Topological Groupoids.. Aequationes mathematicae, Tome 1 (1968) pp. 217-234. http://gdmltest.u-ga.fr/item/GDZPPN002022451/