@article{ASNSP_1965_3_19_4_465_0,
     author = {Heins, Albert E.},
     title = {A boundary value problem associated with the {Tricomi} equation},
     journal = {Annali della Scuola Normale Superiore di Pisa - Scienze Fisiche e Matematiche},
     pages = {465--479},
     publisher = {Scuola normale superiore},
     volume = {Ser. 3, 19},
     number = {4},
     year = {1965},
     mrnumber = {193382},
     zbl = {0151.14601},
     language = {en},
     url = {http://www.numdam.org/item/ASNSP_1965_3_19_4_465_0/}
}