@article{SM_2001_192_5_a0,
     author = {J. Brinkhuis},
     title = {On the {Fermat--Lagrange} principle for mixed smooth convex extremal problems},
     journal = {Sbornik. Mathematics},
     pages = {641--649},
     publisher = {mathdoc},
     volume = {192},
     number = {5},
     year = {2001},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2001_192_5_a0/}
}