My books were randomly purchased, though I think the books at the top of my list are more useful to someone newly learning about the techniques for dehydration.
Bell, Mary T. - Complete Dehydrator Cookbook (©1994)
This was the first book where I started to understand what to do.
Hertzberg, Ruth; Vaughan, Beatrice; Greene, Janet - The New Putting Food By (©1973, Third printing 1983)
This book includes information on canning, freezing, etc.; there is one chapter on drying. Some of the modern methods are now a bit antiquated, but there are plenty of explanations why certain issues are important. From the reference section, I found links to USDA
National Center for Home Food Preservation - Drying
Drying Foods at Home - National Agricultural Library
Keogh, Michelle - Déshydrater Les Aliments Chez Soi ©2015, 2016 (Dehydrating at Home)
Ms Keogh designed several snacks for feeding her family. I never found the book in English, though used English versions are available online. I've found it very entertaining to puzzle out exactly what she's saying.
Gangloff, Tammy; Gangloff, Steven; Ferguson, September The Ultimate Dehydrator Cookbook (©2014)
Bell, Mary T. - Food Drying With an Attitude (©2008)