@article{MZ_1975__143_172233,
     author = {Jens Frehse},
     title = {Two {Dimensional} {Variational} {Problems} with {Thin} {Obstacles.}},
     journal = {Mathematische Zeitschrift},
     pages = {279--288},
     publisher = {mathdoc},
     volume = {143},
     year = {1975},
     zbl = {0295.49003},
     url = {http://geodesic.mathdoc.fr/item/MZ_1975__143_172233/}
}