@article{702421,
     title = {Approximation solvability of nonlinear equations},
     booktitle = {Nonlinear Analysis, Function Spaces and Applications},
     series = {GDML\_Books},
     publisher = {BSB B. G. Teubner Verlagsgesellschaft},
     address = {Leipzig},
     year = {1982},
     pages = {234-257},
     mrnumber = {MR685002},
     zbl = {0507.47037},
     url = {http://dml.mathdoc.fr/item/702421}
}

Webb, J. R. L. Approximation solvability of nonlinear equations, dans Nonlinear Analysis, Function Spaces and Applications, GDML_Books,  (1982), pp. 234-257. http://gdmltest.u-ga.fr/item/702421/