IK Multimedia's iRig Acoustic pickup is insanely small and works with your phone or tablet - gearnews.com
SKYSONIC JOY II Acoustic Guitar Pickup Piezo Mic Dual Pickup Modes with Volume Controls Easy Installation for 36 42 Inch Guitar|Guitar Parts & Accessories| - AliExpress
Acoustic Pickups & How to Make Them Sound Their Best - Radial Engineering
Acoustic Pickups & How to Make Them Sound Their Best - Radial Engineering