APA

Walker R. H., . (1972). Preserving a Heritage : Final Report to the President and Congress of the National Parks Centennial Commission : Washington, D.C. [Place of publication not identified]: publisher not identified.

Chicago

Walker Ronald H, . 1972. Preserving a Heritage : Final Report to the President and Congress of the National Parks Centennial Commission : Washington, D.C. [Place of publication not identified]: publisher not identified.

Harvard

Walker R. H., . (1972). Preserving a Heritage : Final Report to the President and Congress of the National Parks Centennial Commission : Washington, D.C. [Place of publication not identified]: publisher not identified.

MLA

Walker Ronald H, . Preserving a Heritage : Final Report to the President and Congress of the National Parks Centennial Commission : Washington, D.C. [Place of publication not identified]: publisher not identified. 1972.