@article{701474,
     title = {On boundary value problem of Neumann type for hypercomplex function with values in a Clifford algebra},
     booktitle = {Proceedings of the Winter School "Geometry and Physics"},
     series = {GDML\_Books},
     publisher = {Circolo Matematico di Palermo},
     address = {Palermo},
     year = {1990},
     pages = {[213]-226},
     mrnumber = {MR1061803},
     zbl = {0713.35060},
     url = {http://dml.mathdoc.fr/item/701474}
}

Xu, Zhenyuan. On boundary value problem of Neumann type for hypercomplex function with values in a Clifford algebra, dans Proceedings of the Winter School "Geometry and Physics", GDML_Books,  (1990), pp. [213]-226. http://gdmltest.u-ga.fr/item/701474/