@article{GDZPPN00218169X,
title = {A generalized Goursat problem for elliptic equations.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {222},
year = {1966},
pages = {1-13},
zbl = {0132.07503},
url = {http://dml.mathdoc.fr/item/GDZPPN00218169X}
}
Aziz, A.K.; Gilbert, R.P. A generalized Goursat problem for elliptic equations.. Journal für die reine und angewandte Mathematik, Tome 222 (1966) pp. 1-13. http://gdmltest.u-ga.fr/item/GDZPPN00218169X/