@article{01702490,
title = {Principal fibre bundles with structural Lie groupoid.},
journal = {Balkan Journal of Geometry and its Applications (BJGA)},
volume = {6},
year = {2001},
pages = {39-48},
zbl = {0991.22002},
language = {en},
url = {http://dml.mathdoc.fr/item/01702490}
}
Ivan, Gheorghe. Principal fibre bundles with structural Lie groupoid.. Balkan Journal of Geometry and its Applications (BJGA), Tome 6 (2001) pp. 39-48. http://gdmltest.u-ga.fr/item/01702490/