@article {pierrakeas2004comparative,
	title = {A comparative study of dropout rates and causes for two different distance education courses},
	journal = {The International Review of Research in Open and Distributed Learning},
	volume = {5},
	number = {2},
	year = {2004},
	author = {Christos J. Pierrakeas and Xeno, Michalis and Panagiotakopoulos, Christos and Vergidis, Dimitris}
}
