“A Belgian author, entrepreneur, visionary, lawyer and peace activist; he is one of several people who have been considered the father of information science, a field he called “documentation”. Otlet created the Universal Decimal Classification, one of the most prominent examples of faceted classification. Otlet was responsible for the widespread adoption in Europe of the standard American 3×5 inch index card used until recently in most library catalogs around the world (by now largely displaced by the advent of online public access catalogs (OPAC)). Otlet wrote numerous essays on how to collect and organize the world's knowledge, culminating in two books, the Traité de Documentation (1934) and Monde: Essai d'universalisme (1935).”

• Paul_Otlet
• bibliography of the works of Paul Otlet http://people.lis.illinois.edu/~wrayward/otlet/otbib.htm
• “International organisation and dissemination of knowledge : selected essays of Paul Otlet (1990)” https://archive.org/details/internationalorg00otle
• “The Universe of Information: the Work of Paul Otlet for Documentation and International Organisation” https://www.ideals.illinois.edu/handle/2142/651