@article{FPM_2001_7_1_a11,
     author = {R. Hildebrand},
     title = {Classification of phase portraits of optimal syntheses},
     journal = {Fundamentalʹna\^a i prikladna\^a matematika},
     pages = {199--233},
     publisher = {mathdoc},
     volume = {7},
     number = {1},
     year = {2001},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FPM_2001_7_1_a11/}
}