@article{IVM_1989_12_a7,
     author = {B. Ya. Solon},
     title = {Degrees of rigid sets},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {44--47},
     publisher = {mathdoc},
     number = {12},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1989_12_a7/}
}