@article{10_4153_CJM_1971_098_0,
     author = {Nelson, Evelyn},
     title = {The {Lattice} of {Equational} {Classes} of {Commutative} {Semigroups}},
     journal = {Canadian journal of mathematics},
     pages = {875--895},
     year = {1971},
     volume = {23},
     number = {5},
     doi = {10.4153/CJM-1971-098-0},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1971-098-0/}
}