@article{SF_1976__13_134207,
     author = {V.M. Sirjaev},
     title = {Semilattices of width 2.},
     journal = {Semigroup forum},
     pages = {149--177},
     publisher = {mathdoc},
     volume = {13},
     year = {1976},
     zbl = {0354.06001},
     url = {http://geodesic.mathdoc.fr/item/SF_1976__13_134207/}
}