I like books by Carol Armstrong, Susan Taylor Propst, Bea Oglesby just to name a few authors for patterns
2 of my favorite books for technique are:
Applique the Basics and Beyond: The Complete Guide to Successful Machine and Hand Techniques with Dozens of Designs to Mix and Match
Applique Workshop: Mix and Match 10 Techniques to Unlock Your Creativity
This one by sue nickels is also good:
Machine Applique: A Sampler of Techniques