Cutts, Martin. Oxford Quick Reference Plain English Guide. Oxford: Oxford University Press, 1995.

Cutts, Martin. Oxford Guide to Plain English, Third Edition. Oxford: Oxford University Press, 2009.

European Union. How to write clearly, available in more than 20 languages.

http://bookshop.europa.eu/is-bin/INTERSHOP.enfinity/WFS/EU-Bookshop-Site/en_GB/-/EUR/ViewPublication-Start?PublicationKey=HC3010536

Multiculturalism and Citizenship Canada. Plain Language Clear and Simple. Ottawa: Minister of Supply and Services Canada, 1991.

Stephens, Cheryl, ed. Plain Language in Plain English. Vancouver: Plain Language Wizardry, 2010

U.S. Securities and Exchange Commission: A Plain English Handbook. Washington, D.C., 1998.

Government of Canada: Plain Language, Clear and Simple. You can get a free PDF of this 1991 guide and its 1994 companion guide for trainers on the Clear Communication Wiki at http://clear-communication.wikia.com/wiki/Training. Also available in French.