@article{CMH_1957__32_139151,
     author = {Pierre-Denis Meth\'ee},
     title = {L'\'equation des ondes avec second membre invariant},
     journal = {Commentarii mathematici Helvetici},
     pages = {153--164},
     publisher = {mathdoc},
     volume = {32},
     year = {1957},
     zbl = {0079.32904},
     url = {http://geodesic.mathdoc.fr/item/CMH_1957__32_139151/}
}