Bibliografia on-line:

• C. J. van RIJSBERGEN (1981). Information Retrieval. http://www.dcs.gla.ac.uk/Keith/Preface.html
• Christopher D. Manning, Prabhakar Raghavan and Hinrich Schutze (2008). Introduction to Information Retrieval. Cambridge University Press. http://www-csli.stanford.edu/~schuetze/information-retrieval-book.html
• Ed Greengrass (2000). Information Retrieval: A Survey. http://www.csee.umbc.edu/csee/research/cadip/readings/IR.report.120600.book.pdf