@article{CM_1938__5__208_0,
     author = {Pinl, M.},
     title = {Zur Existenztheorie und Klassifikation totalisotroper Fl\"achen},
     journal = {Compositio Mathematica},
     pages = {208--238},
     publisher = {Johnson Reprint Corporation},
     volume = {5},
     year = {1938},
     zbl = {0018.17104},
     language = {de},
     url = {http://www.numdam.org/item/CM_1938__5__208_0/}
}

Pinl, M. Zur Existenztheorie und Klassifikation totalisotroper Flächen. Compositio Mathematica, Tome 5 (1938) , pp. 208-238. http://www.numdam.org/item/CM_1938__5__208_0/