@article{SM_1972_18_1_a6,
     author = {R. B. Treger},
     title = {Rings with a~free semigroup of invertible ideals},
     journal = {Sbornik. Mathematics},
     pages = {101--110},
     publisher = {mathdoc},
     volume = {18},
     number = {1},
     year = {1972},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1972_18_1_a6/}
}