Johnson, David Gale <br/><br/>
Grain yields and the American food supply: an analysis of yield changes and possibilities / 
David Gale Johnson, Robert L. Gustafson 
 - Chicago :  Chicago University Press,  1962 
 - xii, 146p. :  ill. ;  23 cm. 
<br/><br/>Includes bibliographical references and index. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Seeds<br/>Crops and climate<br/>Crop yield<br/>Grain
<br/><br/><label>Dewey Class. No.: </label>633.101 Us  / JOH