@article{CMUC_1973__14_1_a2,
     author = {Petry, Walter},
     title = {Existence theorems for operator equations and nonlinear elliptic boundary-value problems},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {27--46},
     publisher = {mathdoc},
     volume = {14},
     number = {1},
     year = {1973},
     mrnumber = {0320830},
     zbl = {0255.35040},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1973__14_1_a2/}
}