Three reference textbooks are available openly: * Introduction to Information Retrieval, http://informationretrieval.org/ http://informationretrieval.org/ * I

Three reference textbooks are available openly: * Introduction to Information Retrieval, http://informationretrieval.org/ http://informationretrieval.org/ * Information Retrieval in Practice, http://www.search-engines-book.com/ http://www.search-engines-book.com/ * Entity-Oriented Search, https://eos-book.org/ https://eos-book.org/ Modern Information Retrieval is also a classic reference. Not openly available but some contents are (were?) available online. Their site seems to be down but the Internet Archive has a copy. Additional resources here: * https://nlp.stanford.edu/IR-book/information-retrieval.html https://nlp.stanford.edu/IR-book/information-retrieval.html http://web.archive.org/web/20220708135205/http://grupoweb.upf.es/mir2ed/ http://web.archive.org/web/20220708135205/http://grupoweb.up...