The second edition of the WRB was presented at the 18th World Congress of
Soil Science 2006 in Philadelphia, USA (book: IUSS Working Group WRB, 2006;
file: ftp://ftp.fao.org/agl/agll/docs/wsrr103e.pdf. After publication, some errors and
needs for improvement were identified, and an electronic update was published in
2007 http://www.fao.org/fileadmin/templates/nr/images/resources/pdf_documents/
wrb2007_red.pdf.