@article{SM_1992_71_2_a16,
     author = {V. L. Levin},
     title = {A~formula for the optimal value in the {Monge--Kantorovich} problem with a~smooth cost function, and a~characterization of cyclically monotone mappings},
     journal = {Sbornik. Mathematics},
     pages = {533--548},
     publisher = {mathdoc},
     volume = {71},
     number = {2},
     year = {1992},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1992_71_2_a16/}
}