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@article{MT_1996_30_a5, author = {O. V. Kudinov}, title = {Compressed systems of finite approximations for sets in the class $\Sigma_2^0$}, journal = {Matemati\v{c}eskie trudy}, pages = {111--113}, publisher = {mathdoc}, volume = {30}, year = {1996}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MT_1996_30_a5/} }
O. V. Kudinov. Compressed systems of finite approximations for sets in the class $\Sigma_2^0$. Matematičeskie trudy, Tome 30 (1996), pp. 111-113. http://geodesic.mathdoc.fr/item/MT_1996_30_a5/