@article{AIHPC_1990__7_2_97_0,
     author = {Cellina, A. and Colombo, G.},
     title = {On a classical problem of the calculus of variations without convexity assumptions},
     journal = {Annales de l'I.H.P. Analyse non lin\'eaire},
     pages = {97--106},
     publisher = {Gauthier-Villars},
     volume = {7},
     number = {2},
     year = {1990},
     mrnumber = {1051230},
     zbl = {0702.49002},
     language = {en},
     url = {http://www.numdam.org/item/AIHPC_1990__7_2_97_0/}
}