@article{ASNSP_1974_4_1_1-2_131_0,
     author = {De Simon, Luciano and Torelli, Giovanni},
     title = {Linear second order differential equations with discontinuous coefficients in {Hilbert} spaces},
     journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
     pages = {131--154},
     publisher = {Scuola normale superiore},
     volume = {Ser. 4, 1},
     number = {1-2},
     year = {1974},
     mrnumber = {388168},
     zbl = {0318.35055},
     language = {en},
     url = {http://www.numdam.org/item/ASNSP_1974_4_1_1-2_131_0/}
}