@article{ASNSP_1980_4_7_3_375_0,
     author = {Nussbaum, Roger D.},
     title = {A quadratic integral equation},
     journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
     pages = {375--480},
     publisher = {Scuola normale superiore},
     volume = {Ser. 4, 7},
     number = {3},
     year = {1980},
     mrnumber = {597547},
     zbl = {0454.45001},
     language = {en},
     url = {http://www.numdam.org/item/ASNSP_1980_4_7_3_375_0/}
}