@article {MR2230648,
	title = {Relative abelian kernels of some classes of transformation monoids},
	journal = {Bull. Austral. Math. Soc.},
	volume = {73},
	number = {3},
	year = {2006},
	pages = {375{\textendash}404},
	issn = {0004-9727},
	doi = {10.1017/S0004972700035413},
	url = {http://dx.doi.org/10.1017/S0004972700035413},
	author = {Cordeiro, E. and Delgado, M. and Fernandes, V. H.}
}
