http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
"Chapter 6.2 of Section A, National Field Manual for the Collection of Water-Quality Data, Book 9, Handbooks for Water-Resources Investigations."
"Supersedes USGS Techniques of Water-Resources Investigations, Book 9, Chapter A6.2, Version 3.0."
Includes bibliographical references (pages 18-19).