Adobe LiveCycle Designer: Creating Dynamic PDF and HTML5 Forms for Desktop and Mobile Applications (2nd Edition)
http://blogs.adobe.com/livecycle/2013/11/adobe-livecycle-designer-book -2nd-edition-released.html
The 1st edition of this book was the "missing manual" for me to get going with Designer. If you're starting with Designer or want to learn more it's a great book.