@article{PIM_1997_N_S_61_75_a8,
     author = {Vladimir Jankovi\'c},
     title = {On {Necessary} {Conditions} in the {Calculus} of {Variations}},
     journal = {Publications de l'Institut Math\'ematique},
     pages = {61 },
     publisher = {mathdoc},
     volume = {_N_S_61},
     number = {75},
     year = {1997},
     zbl = {0946.49014},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PIM_1997_N_S_61_75_a8/}
}