@article{IVM_1973_10_a2,
     author = {Yu. I. Volkov},
     title = {Certain relations that are connected with semigroups of operators},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {23--28},
     publisher = {mathdoc},
     number = {10},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1973_10_a2/}
}