@article{SF_1971__2_133807,
     author = {T. Evans},
     title = {The lattice of semigroup varieties.},
     journal = {Semigroup forum},
     pages = {1--43},
     publisher = {mathdoc},
     volume = {2},
     year = {1971},
     zbl = {0225.20043},
     url = {http://geodesic.mathdoc.fr/item/SF_1971__2_133807/}
}