@article{MZ_1981__178_173118,
     author = {Michael Wiegner},
     title = {On {Two-Dimensional} {Elliptic} {Systems} with a {One-sided} {Condition.}},
     journal = {Mathematische Zeitschrift},
     pages = {493--500},
     publisher = {mathdoc},
     volume = {178},
     year = {1981},
     zbl = {0474.35046},
     url = {http://geodesic.mathdoc.fr/item/MZ_1981__178_173118/}
}