@article{TMF_1973_15_1_a13,
     author = {B. I. Zhilinskii and N. F. Stepanov},
     title = {Minimization of the energy functional on a special class of unitary operators},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {146--150},
     publisher = {mathdoc},
     volume = {15},
     number = {1},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1973_15_1_a13/}
}