@article{GDZPPN002306859, title = {Winding Numbers on Surfaces II. Applications.}, journal = {Mathematische Annalen}, volume = {196}, year = {1972}, pages = {131-154}, zbl = {0231.57002}, url = {http://dml.mathdoc.fr/item/GDZPPN002306859} }
Chillingworth, D.R.J. Winding Numbers on Surfaces II. Applications.. Mathematische Annalen, Tome 196 (1972) pp. 131-154. http://gdmltest.u-ga.fr/item/GDZPPN002306859/