American Planning Association Library Classification Scheme
"The Library of the American Planning Association (APA) developed the American Planning Association Library Classification Scheme. It was created to meet the needs of APA’s researchers and members; the scheme focuses specifically on planning and provides a level of practical detail not found in other published systems. In the APA Library, the scheme is used in conjunction with the Library of Congress Classification Scheme. A planning agency or library may choose to use the scheme independently or in conjunction with more broadly based schemes such as Library of Congress or Dewey Decimal."