@article{IVM_1963_5_a8,
     author = {D. B. Kikin},
     title = {Extremal properties of the solutions of certain classes of second-order partial differential equations and their applications to gas flows},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {56--58},
     publisher = {mathdoc},
     number = {5},
     year = {1963},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1963_5_a8/}
}