@article{MZ_1968__104_170926,
     author = {D.H. Martin},
     title = {Canonical {Variables} and {Geodesic} {Fields} for the {Calculus} of {Variations} of {Multiple} {Integrals} in {Parametric.}},
     journal = {Mathematische Zeitschrift},
     pages = {16--27},
     publisher = {mathdoc},
     volume = {104},
     year = {1968},
     zbl = {0162.43202},
     url = {http://geodesic.mathdoc.fr/item/MZ_1968__104_170926/}
}