@article{DAN_1965_165_1_a13,
     author = {Ya. Z. Tsypkin and M. S. Epel'man},
     title = {Criterion for absolute stability of multiply connected sampled-data systems with nonstationary characteristics of the nonlinear elements},
     journal = {Doklady Akademii Nauk},
     pages = {51--54},
     publisher = {mathdoc},
     volume = {165},
     number = {1},
     year = {1965},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1965_165_1_a13/}
}