The Homeland Security Digital Library (HSDL) is the nation's collection of documents related to homeland security policy, strategy, and organizational management. The HSDL is sponsored by the U.S. Department of Homeland Security's National Preparedness Directorate, FEMA and the Naval Postgraduate School Center for Homeland Defense and Security. The Library is composed of homeland security related documents collected from a wide variety of sources. These include federal, state, tribal, and local government agencies, professional organizations, think tanks, academic institutions, and international governing bodies. Resources are carefully selected and evaluated by a team of librarians and subject-matter specialists.