%0 Journal Article
%A Irwin Kra
%A Bernard Maskit
%T Bases for qualitativ differentials.
%J Commentarii mathematici Helvetici
%D 1982
%P 603-626
%V 57
%I mathdoc
%U http://geodesic.mathdoc.fr/item/CMH_1982__57_139923/
%F CMH_1982__57_139923