1. Head, T. J. “The Varieties of Commutative Monoids”, Nieuw Arch. Wiskunde. III Ser. 16, No. 3, 203–206 (1968).
2. Wismath, S. L. “The Lattice ofVarieties and Pseudovarieties of BandMonoids”, Semigroup Forum 33, No. 1, 187–196 (1986).
3. Pollák, G. “Some Lattices of Varieties Containing Elements Without Cover”, Quad. Ric. Sci. 109, 91–96 (1981).
4. Jackson, M., Lee, E.W. H. “Monoid VarietiesWith Extreme Properties”, http://arxiv.org/abs/1511.08239.
5. Lee, E. W. H. “Inherently Non-Finitely Generated Varieties of Aperiodic Monoids With Central Idempotents”, POMISc.SeminarNotes 423, 166–182 (2014).