@article{IVM_1993_3_a2,
     author = {D. A. Bredikhin},
     title = {The equational theory of relation algebras with positive operations},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {23--30},
     year = {1993},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1993_3_a2/}
}