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@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/} }
B. Ya. Solon. Degrees of rigid sets. Izvestiâ vysših učebnyh zavedenij. Matematika, no. 12 (1989), pp. 44-47. http://geodesic.mathdoc.fr/item/IVM_1989_12_a7/