@article{ZNSL_2004_312_a13,
     author = {V. L. Levin},
     title = {Optimality conditions and exact solutions to the two-dimensional {Monge--Kantorovich} problem},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {150--164},
     publisher = {mathdoc},
     volume = {312},
     year = {2004},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2004_312_a13/}
}