@article{MAN_1927__97_182661,
     author = {R. Courant},
     title = {\"Uber direkte {Methoden} in der {Variationsrechnung} und \"uber verwandte {Fragen}},
     journal = {Mathematische Annalen},
     pages = {711--736},
     publisher = {mathdoc},
     volume = {97},
     year = {1927},
     zbl = {53.0488.02},
     url = {http://geodesic.mathdoc.fr/item/MAN_1927__97_182661/}
}