@article{AIHPC_1989__6_5_347_0,
     author = {Schulz, Friedmar},
     title = {Univalent solutions of elliptic systems of {Heinz-Lewy} type},
     journal = {Annales de l'I.H.P. Analyse non lin\'eaire},
     pages = {347--361},
     publisher = {Gauthier-Villars},
     volume = {6},
     number = {5},
     year = {1989},
     mrnumber = {1030855},
     zbl = {0698.35055},
     language = {en},
     url = {http://www.numdam.org/item/AIHPC_1989__6_5_347_0/}
}