World reference base for soil resources, 2006 : a framework for international classification, correlation and communication.
Food and Agriculture Organization of the United Nations.
International Union of Soil Sciences.
International Soil Reference and Information Centre.
Rome : Food and Agriculture Organization of the United Nations,
2006.
Includes bibliographical references (p. 121-122).
Soils
Also issued online.
ftp://ftp.fao.org/docrep/fao/009/a0510e/a0510e00.pdf