@article {journals/ipm/PallisAV07,
	title = {Validation and interpretation of Web users{\textquoteright} sessions clusters},
	journal = {Inf. Process. Manage.},
	volume = {43},
	number = {5},
	year = {2007},
	pages = {1348-1367},
	author = {Pallis, George and Angelis, Lefteris and Athena Vakali}
}