labor and services, for purposes of this Act, including preserving or providing access to sites and other resources relating to the Civil War defenses of Washington. (d) Other cooperative agreements In addition to the authority provided by section 5(a), the Secretary may enter into cooperative agreements with State governments, units of local government, organizations, or individuals to further the purposes of the Act, including to provide visitor services and administrative facilities within reasonable proximity to the National Historical Park. (e) Marking of historical sites The Secretary may identify significant federally or nonfederally owned sites relating to the Civil War history in Washington and adjacent environs in northern Virginia and Montgomery County, Maryland, and, with the consent of the owner or owners thereof, mark them appropriately and make reference to them in any interpretive literature. 8. Definitions For the purposes of this Act, the following definitions apply: (1) National Historical Park The term National Historical Park means the Civil War Defenses of Washington National Historical Park designated by section 3. (2) Secretary The term Secretary means the Secretary of the Interior.