Category Archives: encyclopedia



o    APUPA is a concept developed by the father of Library Science, Shiyali Ramamrita Ranganathan, to define the natural and hierarchical relationship of materials in a bibliographic classification scheme.


o    APUPA stands for Alien-Penumbral-Umbral-Penumbral-Alien.


o    Umbral represents the exact information source matching the subject area. The Penumbral sources are closely related. The Alien sources are unrelated.


o    APUPA explains how a classification scheme’s linear structure creates meaning for the user by bringing together closely related subject areas. A user naturally views the most relevant information source (Umbral) first, then moves either left or right to related resources (Penumbral), and then to unrelated resources (Alien).


o    APUPA patterns are dynamic. Any book or other resource within a classification scheme can be an Umbral source and any resource can also be Penumbral or Alien, depending on the subject.


o    If you are seeking a book on growing roses, that book is your Umbral source. Books about pruning roses, which is a related topic but not exactly the same, are Penumbral sources. Books about composting would be Alien, or unrelated sources.



An encyclopedia (also spelled encyclopaedia or encyclopædia) is a type of reference work – a compendium holding a summary of information from either all branches of knowledge or a particular branch of knowledge. Encyclopedias are divided into articles or entries, which are usually accessed alphabetically by article name. Encyclopedia entries are longer and more detailed than those in most dictionaries. Generally speaking, unlike dictionary entries, which focus on linguistic information about words, encyclopedia articles focus on factual information to cover the thing or concept for which the article name stands.