@incollection{AST_1979__66-67__90_0,
     author = {Po\'enaru, V.},
     title = {Appendice : {Spines} des vari\'et\'es de dimension $2$},
     booktitle = {Travaux de Thurston sur les surfaces - S\'eminaire Orsay},
     series = {Ast\'erisque},
     pages = {90--92},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {66-67},
     year = {1979},
     zbl = {0446.57011},
     language = {fr},
     url = {http://archive.numdam.org/item/AST_1979__66-67__90_0/}
}