@article{GDZPPN002052695,
title = {\"Uber Freisysteme (lineare Freigebilde).},
journal = {Commentarii mathematici Helvetici},
volume = {11},
year = {1938},
pages = {62-76},
zbl = {0019.32503},
url = {http://dml.mathdoc.fr/item/GDZPPN002052695}
}
Finsler, Paul. Über Freisysteme (lineare Freigebilde).. Commentarii mathematici Helvetici, Tome 11 (1938) pp. 62-76. http://gdmltest.u-ga.fr/item/GDZPPN002052695/