Stated in "Introduction to Permaculture" by Bill Mollison & Reny Mia Slay

Principles from Permaculture a Designers' Manual by Bill Mollison.

This is the definitive Permaculture design manual in print since 1988. It is the textbook and curriculum for the 72-hour Certificate course in Permaculture Design.

You may also be interested in this podcast, where Geoff Lawton covers the contents of the Designers' Manual in about an hour.

Principles proposed by David Holmgren in his book Permaculture: Principles and Pathways Beyond Sustainability. David Holmgren, Holmgren Design Services, Australia, 2003, 320pp. Principles from "Permaculture: Principles and Pathways Beyond Sustainability" by David Holmgren