Sellars, R. W. (1997). Preserving nature in the national parks: A history : with a new preface and epilogue. Yale University Press.
Chicago-referens (17:e uppl.)Sellars, Richard West. Preserving Nature in the National Parks: A History : With a New Preface and Epilogue. New Haven: Yale University Press, 1997.
MLA-referens (9:e uppl.)Sellars, Richard West. Preserving Nature in the National Parks: A History : With a New Preface and Epilogue. Yale University Press, 1997.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.