Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{CMH_1982__57_139923, author = {Irwin Kra and Bernard Maskit}, title = {Bases for qualitativ differentials.}, journal = {Commentarii mathematici Helvetici}, pages = {603--626}, publisher = {mathdoc}, volume = {57}, year = {1982}, zbl = {0527.30036}, url = {http://geodesic.mathdoc.fr/item/CMH_1982__57_139923/} }
Irwin Kra; Bernard Maskit. Bases for qualitativ differentials.. Commentarii mathematici Helvetici, Tome 57 (1982), pp. 603-626. http://geodesic.mathdoc.fr/item/CMH_1982__57_139923/