YUCCA (vol. I)  In the SOUTHWEST and MIDWEST of the USA and CANADA
                                    The dehiscent fruited species. Revised ed. 2000. 256 pages, Hard bound, glossy paper,
                                    150 color photos, 10 distribution maps, drawings (seeds, inflorescence, root systems),
                                    text in English, with german summary.
                                    PRICE: DM 165,- -- plus pp.
                                    Published in May 2000.
More information on the authors website.

YUCCA (vol. II)  In the SOUTHWEST and MIDWEST of the USA and CANADA
                                    Indehiscent-fruited species. Revised ed. 2000. 340 pages, Hard bound, glossy paper,
                                    289 color photos, distribution maps, drawings (seeds, inflorescence, root systems),
                                    text in English, with german summary.
                                    Published in 2002.
More information on the authors website.

YUCCA (vol. III) Mexico
                                    Indehiscent-fruited  and Dehiscent fruited species. published 2004, 304 pages, Hard bound, glossy paper,
                                    252 color photos, 7 maps, 8 drawings and 18 SEM's.
                                    text in English, with german summary.
                                    Published in 2002.
More information on the authors website.

IRISH, MARY & GARY; 2000, "Agaves, Yuccas, and Related Plants: A Gardener's Guide"
                                    384 pages, 100 color photos, 18 line drawings, 1 map, 6 x 9", hardcover, published June 2000
                                    US$34.95

Of the above books Hochstaetter's are the most serious, and most accurate, and the distribution maps are very helpful combined with all the details written in the book. While the book by the Irish's are for the gardener who would like to have some all-round information about Agaves, Yuccas, and Related Plant. The hardiness rating in the book by the Irish's are very exaggerated! while the hardiness ratings in Hochstaetter's book is a lot closer to the reality! at least for the climate I live in!

Thomas Boeuf;  Yucca & Co. (2007),
                                    Soft cover, 24,5 x 17,5 cm 192 pages, 289 color photos.
                                    (German language)
A well written book, with many excellent photos. Many cultivation tips, if you want to know more about cultivation of Yuccas in central Europe, you will find it in this book.
More information on the authors website

Most Yucca literature is published in various journals, there has only been published a few Yucca books in the past, they are:

TRELEASE, W.; 1902, The Yucceae,
                                    Missouri Bot. Gard. Ann. Rpt. 13:27-133, USA.

MOLON, G., 1914; Le Yucche,
                                     published by Ulrico Holpli Milano, text in Italian.
                                     Most if not all (at that time) know hybrids are listed in this book, but MOLON did make some
                                     errors about the Sprenger hybrids! If he made other mistakes I don't know, while the text is in Italian!

MCKELVEY, S., 1938; Yuccas of the southwestern United States, Part I
                                    The Arnold Arboretum of Harvard University, Jamaica Plain, Mass., USA.

MCKELVEY, S., 1947; Yuccas of the southwestern United States, Part II
                                    The Arnold Arboretum of Harvard University, Jamaica Plain, Mass., USA.

WEBBER, 1953; Yuccas of the Southwest
                                    Agriculture Monograph No. 17, U.S. Department of Agriculture, USA.

GENTRY, H. S., 1972; The Agave Family in Sonora,
                                    USDA Agri. Handbook No. 399:154-170

Most of the other literature there are available, are from various Journal, Botanical reports, Floras etc. if you need more references look at my list of Yucca names.

The Yucca Plant and the Yucca moth:  Good site with excellent explanation on the symbioses of the Yucca plant and the Yucca moth

Vascular Plant Image Gallery (Agavaceae):  Site with photos of Yucca's from mostly Big Ben area Texas