@incollection{JEDP_1977____164_0, author = {Pham The Lai and Robert, Didier}, title = {Valeurs propres d'une classe d'\'equations diff\'erentielles singuli\`eres sur une demi-droite}, booktitle = {}, series = {Journ\'ees \'equations aux d\'eriv\'ees partielles}, pages = {164--171}, publisher = {Ecole polytechnique}, year = {1977}, mrnumber = {80j:34026}, language = {fr}, url = {http://archive.numdam.org/item/JEDP_1977____164_0/} }