Classification and Shelflisting Manual (2013)
Instructions for establishing and using classes in Library of Congress Classification. Developed and maintained by Library of Congress, Policy and Standards Division. Succeeds Subject Cataloging Manual: Shelflisting and Subject Cataloging Manual: Classification.
Available online Classification and Shelflisting Manual (with selected updates) for download
Available in Cataloger's Desktop
Available online Shelflisting Instruction Sheets Guide
Further information here
Dewey Decimal Classification (DDC) Dewey Decimal Classification & Relative Index, 23rd ed. (2011)
Available also in Abridged Edition 15 (2012)
Available in print
Available online Dewey Decimal Classification
Available in Cataloger’s Desktop with subscriptions to both Cataloger’s Desktop and WebDewey.
GPO Classification Manual, rev. July 1993
Principles and policies for use of Superintendent of Documents Classification for publications of the United States government. Developed by Superintendent of Documents, United States Government Printing Office.
Available online GPO Classification Manual
Library of Congress Classification (LCC)
Forty-one separate schedules, in different editions, for classes A–Z. Developed and maintained by Library of Congress, Policy and Standards Division. LCC is distributed by the Library's Cataloging Distribution Service in two forms.
Available via Classification Web, an online product that includes not only LCC but also the text of Library of Congress Subject Headings (LCSH). A full set of LCC records in MARC 21 or MARCXML format, as well as subscriptions to a weekly update service
41 print-ready PDF volumes (called schedules), are available on the World Wide Web. A detailed outline of LCC is available on the World Wide Web.
List of Classes
Official listing of publications available for selection by depository libraries participating in the Federal Depository Library Program (FDLP). U.S. government agencies assigned in Superintendent of Documents Classification by the U.S. Government Printing Office.
Available to download List of Classes print (updated semiannually).
Data files available in file repository (updated monthly).
National Library of Medicine (NLM) Classification 2016
Developed by United States National Library of Medicine for the arrangement of library materials in the field of medicine and related sciences.
Available online National Library of Medicine (NLM) Classification
Universal Decimal Classification (UDC)
Maintained by the UDC Consortium (UDCC) in a database of over 70,000 records.
Available online UDCS Linked Data
Available online Structured data published in SKOS (SML/RDF) format.