@article{NUMA_1970__16_132016,
     author = {J.W. DANIEL},
     title = {A {Simple,} {Global,} {Complementary} {Variational} {Principle.}},
     journal = {Numerische Mathematik},
     pages = {52--57},
     publisher = {mathdoc},
     volume = {16},
     year = {1970},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1970__16_132016/}
}