The two BEST books (IMHO) for Domestic Machine quilting are:
Heirloom Machine Quilting by Harriett Hargrave. You can can pick it up used on Amazon for as little as $5
https://www.amazon.com/Heirloom-Mach...ag=googhydr-20
And Guide to Machine quilting by Diane Gaudynski, which you can get used from Amazon for the price of shipping
https://www.amazon.com/dp/1574327968...YC8GAJ139MT3CX
Both books are a great resource for any quilters library. Diane's books talks extensively about threads with wonderful close up pics showing the differences when quilting with different weights and types of threads.