Marshall, Perry S. Industrial Ethernet: a pocket guide, c2002: CIP t.p. (Perry S. Marshall)

Evolution 2.0, 2015: E-Cip t.p. (Perry Marshall)

www.amazon.com/Evolution-2-0-Breaking-Deadlock, Feb. 17, 2015: (Perry Marshall, author of Industrial Ethernet, Entrepreneur magazine's ultimate guide to Google AdWords, and 80/20 sales and marketing)

Facebook advertising, c2020: t.p. (Perry Marshall)

Wikipedia, viewed Dec. 11, 2020 (Perry Sink Marshall is an American online marketing consultant, and author of books on internet marketing. He is a Christian proponent of continuationism and evolutionary creation, and has lectured and written on these topics) https://en.wikipedia.org/wiki/Perry_Marshall

Google knowledge panel, viewed Dec. 11, 2020 (Perry Marshall, b. Apr. 10, 1969) https://www.google.com/search?q=Perry+Marshall