@article{MAN_1967__171_161561,
     author = {A. LIESEN},
     title = {Feldtheorie in der {Variationsrechnung} mehrfacher {Integrale.} {I.}},
     journal = {Mathematische Annalen},
     pages = {194--218},
     publisher = {mathdoc},
     volume = {171},
     year = {1967},
     zbl = {0168.09902},
     url = {http://geodesic.mathdoc.fr/item/MAN_1967__171_161561/}
}