@article{GDZPPN00233156X, title = {The Classification of Maps of Nonorietable Surfaces.}, journal = {Mathematische Annalen}, volume = {280}, year = {1988}, pages = {687-702}, zbl = {0656.57001}, url = {http://dml.mathdoc.fr/item/GDZPPN00233156X} }
Gabai, David; Kazez, William H. The Classification of Maps of Nonorietable Surfaces.. Mathematische Annalen, Tome 280 (1988) pp. 687-702. http://gdmltest.u-ga.fr/item/GDZPPN00233156X/