@article{GDZPPN00227521X, title = {Systems of K-dimensional manifolds in an N-dimensional space}, journal = {Mathematische Annalen}, volume = {105}, year = {1931}, pages = {707-733}, zbl = {0003.16902}, url = {http://dml.mathdoc.fr/item/GDZPPN00227521X} }
Douglas, J. Systems of K-dimensional manifolds in an N-dimensional space. Mathematische Annalen, Tome 105 (1931) pp. 707-733. http://gdmltest.u-ga.fr/item/GDZPPN00227521X/