@article{SF_1974__9_134076,
     author = {Ju.M. Vazenin},
     title = {On the elementary theory of free inverse semigroups.},
     journal = {Semigroup forum},
     pages = {189--195},
     publisher = {mathdoc},
     volume = {9},
     year = {1974},
     zbl = {0299.20050},
     url = {http://geodesic.mathdoc.fr/item/SF_1974__9_134076/}
}