I have put a web page online, which gives an explanation (in French) of such IR concepts for students:
http://www.univ-ag.fr/gerec-f/points_de_depart_recherche/astuces.html
In case this might be useful to some. (But as I understood, what Frederica was actually looking for in the first place was a Bibtex reference to cite as a seminal publication introducing the concepts; and this question has already been answered by previous posts).
Regards,
Pascal Vaillant