Weaver, J. E. and Clements, F. E., "Plant Ecology," 2nd Ed., McGraw-Hill 

 Book Co., New York, N.Y., 1938. 



Whittaker, R. H., "Recent Evolution of Ecological Concepts in Relation to the 

 Eastern Forests of North America," pp. 340-358 in "Fifty Years of Botany," 

 W. C. Steere, Ed., McGraw-Hill Book Co., New York, N.Y., 1958. 



Bases and Units * 189 



