@article{ASNSP_1972_3_26_2_283_0,
     author = {Hager, R. A. and Ross, J.},
     title = {A regularity theorem for linear second order elliptic divergence equations},
     journal = {Annali della Scuola Normale Superiore di Pisa - Scienze Fisiche e Matematiche},
     pages = {283--290},
     publisher = {Scuola normale superiore},
     volume = {Ser. 3, 26},
     number = {2},
     year = {1972},
     mrnumber = {374643},
     zbl = {0256.35027},
     language = {en},
     url = {http://www.numdam.org/item/ASNSP_1972_3_26_2_283_0/}
}