Not a permaculture book per se, though he mentions it from time to time, but probably the best permaculture book (especially for northern gardeners) that I've read in the five or six years I've been studying it. Bonsall has an 84-acre farm in Unity, Maine, on which he raises (with very little rototilling) vegetables, fruits, permacrops, grains, pulses, oilseeds -- and no animals at all. His writing is incisive, witty, clear, easy flowing, a pleasure to read. Topics covered include the vision of a garden without borders, composting, making mulch and green manures, soil and minerals, grassland management, propagating seeds, rocks and water, planting more efficiently (trellises, companion planting, new world vs. old world crops), chapters on crops (veggies, grains, pulses, oilseeds, permacrops), using the harvest by milling, baking, sprouting, freezing, fermenting, dehydrating, etc., and pests and diseases -- usually the most boring (no pun intended) chapter in these books, this is one of the best in Bonsall's. Recommended for northern climate gardeners, especially those not interested in keeping animals.