Summary: The THEORY OF BOOK CLASSIFICATION by Dr. Ranganathan introduces the concept of 'Attachment Document' for related literary productions. The author suggests a comma and serial numbers system for connecting related books instead of using a connecting symbol. The facet formula for book numbering is prescribed with language, form of exposition, year of publication, and a unique accession facet. Various arrangements for form divisions are detailed, emphasizing the need for specific instructions on their use. The canon of a collection number is introduced to classify special documents like reference books separately. Dr. Ranganathan's significant contributions to library science, classification, and his effort to introduce library legislation in India are highlighted, illustrating his profound impact in the field. The book also provides insight into the organization of literature classes, form divisions, and mnemonics for efficient classification, emphasizing the importance of precise categorization in facilitating access to information.