Products of Commutators and Products of Squares in a Free Group. - Leo P. Comerford Jr.; Charles C. Edmunds (Int. J. Algebra Comput., 1994)

Small Semigroups Generating Varieties with Continuum Many Subvarieties. - Charles C. Edmunds; Edmond W. H. Lee; Ken W. K. Lee (Order, 2010)