@article{701766,
     title = {Trivial constraint variational problem},
     booktitle = {Proceedings of the 25th Winter School "Geometry and Physics"},
     series = {GDML\_Books},
     publisher = {Circolo Matematico di Palermo},
     address = {Palermo},
     year = {2006},
     pages = {[67]-74},
     mrnumber = {MR2287126},
     zbl = {1114.70015},
     url = {http://dml.mathdoc.fr/item/701766}
}

Czudková, Lenka; Janová, Jitka; Musilová, Jana. Trivial constraint variational problem, dans Proceedings of the 25th Winter School "Geometry and Physics", GDML_Books,  (2006), pp. [67]-74. http://gdmltest.u-ga.fr/item/701766/