http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
v. 1. Principles, including plant growth reguators. 6th ed.--v. 2. Recommendations, including plant growth regulators. 8th ed.
issued by the British Crop Protection Council edited by J. D. Fryer and R. J. Makepeace.
Volume 1, 6th edition is published as a "companion to volume 2, 8th edition."