@article{VUU_2005_1_a3,
     author = {A. E. Irisov and E. L. Tonkov},
     title = {Sufficient conditions for optimality of {Birkhoff} recurrent motions for differential inclusion},
     journal = {Vestnik Udmurtskogo universiteta. Matematika, mehanika, kompʹ\^uternye nauki},
     pages = {59--74},
     publisher = {mathdoc},
     number = {1},
     year = {2005},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VUU_2005_1_a3/}
}