@article{VMJ_1999_1_4_a0,
     author = {V. P. Andreev and E. I. Gordon},
     title = {Nonstandard theory of classes},
     journal = {Vladikavkazskij matemati\v{c}eskij \v{z}urnal},
     pages = {3--16},
     publisher = {mathdoc},
     volume = {1},
     number = {4},
     year = {1999},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMJ_1999_1_4_a0/}
}