@article {pierrakeas2003evaluating,
	title = {Evaluating and improving educational material and tutoring aspects of distance learning systems},
	journal = {Studies in Educational Evaluation},
	volume = {29},
	number = {4},
	year = {2003},
	pages = {335{\textendash}349},
	publisher = {Pergamon},
	author = {Christos J. Pierrakeas and Xenos, Michalis and Pintelas, Panayiotis}
}
