@article {simidat47,
	title = {Evolutionary algorithms for subgroup discovery in e-learning: A practical application using Moodle data},
	journal = {Expert Systems with Applications},
	volume = {36},
	year = {2009},
	pages = {1632-1644},
	author = {C. Romero and P. Gonz{\'a}lez and S. Ventura and M. J. del Jesus and F. Herrera}
}
