@article{1256059574, author = {Wohlfahrt, Klaus}, title = {An extension of F. Klein's level concept}, journal = {Illinois J. Math.}, volume = {8}, number = {4}, year = {1964}, pages = { 529-535}, language = {en}, url = {http://dml.mathdoc.fr/item/1256059574} }
Wohlfahrt, Klaus. An extension of F. Klein's level concept. Illinois J. Math., Tome 8 (1964) no. 4, pp. 529-535. http://gdmltest.u-ga.fr/item/1256059574/