@inproceedings{1041933,
    title = "Empirical evaluation fo user models and user-adapted systems: a layered evaluation review",
    author = "Karagiannidis, Charalampos and Sampson, Demetrios G. and Brusilovsky, Peter",
    year = "2001",
    pages = "102-107",
    publisher = "Εκδοτικός Οργανισμός Λιβάνη",
    booktitle = "8th Panhellenic Conference in Informatics Proceedings (Volume 2)"
}