@article {MR2050894,
	title = {Abelian kernels of monoids of order-preserving maps and of some of its extensions},
	journal = {Semigroup Forum},
	volume = {68},
	number = {3},
	year = {2004},
	pages = {335{\textendash}356},
	issn = {0037-1912},
	doi = {10.1007/s00233-003-0014-z},
	url = {http://dx.doi.org/10.1007/s00233-003-0014-z},
	author = {Delgado, Manuel and Fernandes, V{\'\i}tor H.}
}
