Soil survey manual / 
by Soil Survey Staff, Bureau of Plant Industry, Soils, and Agricultural Engineering. 
 - Washington :  United States Department of Agriculture,  1951. 
 - Handbook / Department of Agriculture ;  no. 18 .
<br/><br/>Bibliografía: p. 443-445. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Reconocimiento de suelos<br/>Suelos
<br/><br/><label>Index Terms--Genre/Form: </label><br/>Manual