Hays, Samuel P. <br/><br/>
Conservation and the gospel of efficiency:   the progressive conservation movement 1890-1920 / 
Samuel P. Hays 
 - Cambridge:      Harvard University,  1959 
 - 297p. ;  19 cn. 
 - Harvard historical monograph .
<br/><br/>Includes bibliographical references and index. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>History of economic thought<br/>Economic thought
<br/><br/><label>Dewey Class. No.: </label>330.109   / HAY