@article{TM_1995_211_a28,
     author = {M. M. Khapaev},
     title = {Singular differential equations in control and minimization problems},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {411--418},
     publisher = {mathdoc},
     volume = {211},
     year = {1995},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1995_211_a28/}
}