Keys to Soil Taxonomy / 
Soil Survey Staff. 
 - 6th ed. 
 - [Washington, D.C.] :  United States Dept. of Agriculture, Soil Conservation Service,  c1994. 
 - iv, 306 p. ;  28 cm. 
<br/><br/> "This volume includes all revisions of the keys that have so far been approved, replacing the original keys in Soil taxonomy, a basic system of soil classification ... (1975), the work on which this abridged version, first published 1983 is based"--P. ii.  Includes index. 
<br/><br/>Includes bibliographical references. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Soils--Classification.
<br/><br/><label>Dewey Class. No.: </label>SOI  / 631.44