Everything You Need to Know About the 18650 Battery
Amazon.com: Keeppower USB Rechargeable Li-ion AA Batteries 3390mWh Double A Protected Lithium Battery 1.5V 2260mAh High Capacity Fast Charge Included with a 4-in-1 Charging Cable (Pack of 4) : Health & Household
BU-304: Why are Protection Circuits Needed? - Battery University
How to do a correct test and determine whether a 18650 li-ion is a protected or non-protected battery - Quora
The Anatomy of a Protected Battery
Beginner's guide to 18650 battery with easy-to-understand illustration - SkyGenius Online