@article{MZM_1992_51_1_a13,
     author = {V. S. Medvedev},
     title = {The bifurcation of the {\textquotedblleft}blue sky catastrophe{\textquotedblright} on two-dimensional manifolds},
     journal = {Matemati\v{c}eskie zametki},
     pages = {118--125},
     year = {1992},
     volume = {51},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1992_51_1_a13/}
}