@article{GDZPPN002055112, title = {Ein geometrisches Minimumproblem.}, journal = {Commentarii mathematici Helvetici}, volume = {22}, year = {1949}, pages = {103-114}, zbl = {0031.17604}, url = {http://dml.mathdoc.fr/item/GDZPPN002055112} }
Bieri, Hans. Ein geometrisches Minimumproblem.. Commentarii mathematici Helvetici, Tome 22 (1949) pp. 103-114. http://gdmltest.u-ga.fr/item/GDZPPN002055112/