1. The Enhanced Forest Inventory and Analysis Program � National Sampling Design and Estimation Procedures
2. O'Connell, B.M.; Conkling, B.L.; Wilson, A.M.[et al.]. 2017. Forest Inventory and Analysis database: Database description and user guide for phase 2 (version 7.0). Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 830 p. https://www.fia.fs.fed.us/library/database-documentation(accessed May 26, 2017).