@inbook {MR2170754,
	title = {Abelian kernels, solvable monoids and the abelian kernel length of a finite monoid},
	booktitle = {Semigroups and languages},
	year = {2004},
	pages = {68{\textendash}85},
	publisher = {World Sci. Publ., River Edge, NJ},
	organization = {World Sci. Publ., River Edge, NJ},
	doi = {10.1142/9789812702616_0005},
	url = {http://dx.doi.org/10.1142/9789812702616_0005},
	author = {Delgado, Manuel and Fernandes, V{\'\i}tor H.}
}
