@article{CMH_1946__19_138900,
     author = {Hans Bieri},
     title = {Beitrag zur {L\"osung} eines {Randwertproblems} der {Variationsrechnung.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {227--235},
     year = {1946},
     volume = {19},
     url = {http://geodesic.mathdoc.fr/item/CMH_1946__19_138900/}
}