@incollection{AST_1981__82-83__45_0, author = {L\^e D\~{u}ng Tr\'ang}, title = {Limites d'espaces tangents et obstruction {d'Euler} des surfaces}, booktitle = {Caract\'eristique d'Euler-Poincar\'e - S\'eminaire E.N.S. 1978-1979}, series = {Ast\'erisque}, pages = {45--69}, publisher = {Soci\'et\'e math\'ematique de France}, number = {82-83}, year = {1981}, mrnumber = {629123}, zbl = {0495.14023}, language = {fr}, url = {http://www.numdam.org/item/AST_1981__82-83__45_0/} }