@article{RM_1989_44_5_a7,
     author = {A. A. Agrachev},
     title = {One more condition for a conditional extremum},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {189--190},
     publisher = {mathdoc},
     volume = {44},
     number = {5},
     year = {1989},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1989_44_5_a7/}
}