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@article{AL_1984_23_2_a5, author = {A. A. Stepanova}, title = {Groupoids of rank $2$ generating categorical {Horn} classes}, journal = {Algebra i logika}, pages = {193--207}, publisher = {mathdoc}, volume = {23}, number = {2}, year = {1984}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/AL_1984_23_2_a5/} }
A. A. Stepanova. Groupoids of rank $2$ generating categorical Horn classes. Algebra i logika, Tome 23 (1984) no. 2, pp. 193-207. http://geodesic.mathdoc.fr/item/AL_1984_23_2_a5/