Cita APA

National Coal Resource Assessment (Estados Unidos), & National Coal Resource Assessment (Estados Unidos). (2001). 2000 resource assessment of selected coal beds and zones in the Northern and Central Appalachian basin coal regions (Version 1.0.). [Reston, Va.?]: U.S. Geological Survey.

Citación estilo Chicago

National Coal Resource Assessment (Estados Unidos), y National Coal Resource Assessment (Estados Unidos). 2000 Resource Assessment of Selected Coal Beds and Zones in the Northern and Central Appalachian Basin Coal Regions. Version 1.0. [Reston, Va.?]: U.S. Geological Survey, 2001.

Cita MLA

National Coal Resource Assessment (Estados Unidos), y National Coal Resource Assessment (Estados Unidos). 2000 Resource Assessment of Selected Coal Beds and Zones in the Northern and Central Appalachian Basin Coal Regions. Version 1.0. [Reston, Va.?]: U.S. Geological Survey, 2001.