Smith, J. Russell.  Tree Crops:  a Permanent Agriculture.  New York:  Harcourt, Brace and Company, 1929.

Smith’s visionary solution to upland erosion is growing unirrigated tree crops that produce cereal-like foods and nuts.  Should sit on the “family bible shelf” of every permaculturalist.

Solomon, Stephen J. Growing Vegetables West of the Cascades. Seattle:  Sasquatch Books, 1989.

The complete regional gardening textbook.

-------------------------. Backyard Composting. Portland, Ore.: 
George van Patten Publishing, 1992.

Especially useful for its unique discussion of the overuse of compost and a nonideological approach to raising the most nutritious food possible.

Stout, Ruth. Gardening Without Work for the Aging, the Busy and the Indolent. Old Greenwich, Conn.:  Devin-Adair, 1961.

Stout presents the original thesis of permanent mulching.

Turner, Frank Newman. Fertility, Pastures and Cover Crops Based on Nature’s Own Balanced Organic Pasture Feeds. San Diego:  Rateaver, 1975.  Reprinted from the 1955 Faber and Faber, edition.

Organic farming using long rotations, including deeply rooted green manures developed to a high art.  Turner maintained a productive organic dairy farm using subsoiling and long rotations involving tilled crops and semipermanent grass/herb mixtures.

ven der Leeden, Frits, Fred L. Troise, and David K. Todd. The Water Encyclopedia, Second Edition. Chelsea, Mich.:  Lewis Publishers, 1990.

Reference data concerning every possible aspect of water.

Weaver, John E., and William E. Bruner. Root Development of Vegetable Crops. New York:  McGraw-Hill, 1927.

Contains very interesting drawings showing the amazing depth and extent that vegetable roots are capable of in favorable soil.

Widtsoe, John A. Dry Farming:  A System of Agriculture for Countries Under Low Rainfall. New York:  The Macmillan Company, 1920.

The best single review ever made of the possibilities of dry farming and dry gardening, sagely discussing the scientific basis behind the techniques.  The quality of Widtsoe’s understanding proves that newer is not necessarily better.