@article{MM2_1979__30_154673,
     author = {Per-Anders Ivert},
     title = {Regularit\"atsuntersuchungen von {L\"osungen} elliptischer {Systeme} von quasilinearen {Differentialgleichungen} zweiter {Ordnung.}},
     journal = {Manuscripta mathematica},
     pages = {53--88},
     publisher = {mathdoc},
     volume = {30},
     year = {1979},
     zbl = {0429.35033},
     url = {http://geodesic.mathdoc.fr/item/MM2_1979__30_154673/}
}