Roots Demystified: Change Your Gardening Habits to Help Roots Thrive, by Robert Kourik.
A good introductory book to the growth of tree, shrub, and plant roots. Has some material on other things that grow in the soil that interact with roots, and some basic soil science, including a brief chapter on fungus and symbiotic relationships. There are sections on vegetables, shrubs, and trees, how their roots grow and differ, with good planting and care advice. If you have other books with sections on roots, there is little new here. If not, it is a good book to start with. It has a good reference section of current books that we can actually purchase or borrow.
I have read the book, and thumbed through it several times more, and I am still not sure what the author's recommendation for changing my gardening habits to is, there does not seem to be a conclusion or summary. I think, I may be wrong, that he recommends double digging if the soil is poor or compacted, then move on to compost, mulch, and shallow tilling only.
The book is recommended by John Jevons, the "Grow Biointensive" double digging proponent, and it often mentions Ruth Stout, the no dig no work gardening advocate of thick mulching. He draws on the work of John Weaver in the 1920's and 30's, which is good, as Weaver's books are not readily available.
All in all a good book, easy to read presented with a dry sense of humor, solid information, a book I may go back to read again for inspiration, and a bit of reference.