@article{GDZPPN002101688,
title = {The homotopy class of non-singular Morse-Smale vector fields on 3-manifolds.},
journal = {Inventiones mathematicae},
volume = {82},
year = {1985},
pages = {435-452},
zbl = {0622.58018},
url = {http://dml.mathdoc.fr/item/GDZPPN002101688}
}
Yano, Koichi. The homotopy class of non-singular Morse-Smale vector fields on 3-manifolds.. Inventiones mathematicae, Tome 82 (1985) pp. 435-452. http://gdmltest.u-ga.fr/item/GDZPPN002101688/