@article{IVM_1976_2_a9,
     author = {A. N. Trakhtman},
     title = {Subsemigroup graphs, and lattices of subsemigroups},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {69--78},
     publisher = {mathdoc},
     number = {2},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1976_2_a9/}
}