Two eBooks by Tom Turner are available for free digital download in October, 2008 - to celebrate the 10th birthday of the Gardenvisit.com website, in return for your email address. The first is in pdf format (presumably the second will be as well). There are other online ebooks on their website, which may be read for free, but only a page at a time while online, not as a download. The pricing below is taken from the site's info - neither title is available at Amazon.com at the current time.
The free eBooks are:
The Principles of Garden Design by Tom Turner
(ISBN 978-0-9542306-2-3, 45 pages, 130 illustrations, 2008, normal price $15.00)
The eBook explains the 3 classic design principles: gardens should be useful, gardens should be well-made and gardens should be beautiful. The principles come from Vitruvius. They have influenced the design of gardens since ancient times and are as important today as they have always been.
24 Historic Styles of Garden Design by Tom Turner
(ISBN 978-0-9542306-3-0, 84 pages, 230 illustrations, 2008, normal price $19.00)
Giving simple and clear explanations of the use and form of the 24 best-known historic styles of garden design in the west. The period covered extends from the temples and courtyards of Ancient Egypt to the Modern and Postmodern styles of the 21st century, including recent gardens from the Chelsea Flower Show.