Intercropping and the Scientific Basis of Traditional Agriculture. Donald Q. Innis. Intermediate Technology Publications. 1997. 179 pages. Hundreds of references.
Michael Pilarski is a multi-disciplinary thinker and hands-on guy specializing in organic, sustainable agriculture, forestry, agroforestry and permaculture. He is a farmer, tree-planter, author and educator. He has planted 80,000 trees so far.