(18.1) Misconceptions about Stepper Motors Explained - MachineDesign 2017feb18
https://www.machinedesign.com/motors-drives/article/21835161/misconceptions-about-stepper-motors-explained

(18.2) Step Motor Basics - GeckoDrive 2017nov03
https://www.geckodrive.com/support/step-motor-basics.html

(18.3) What is a chopper drive for a stepper motor? - Dantelle Collins, 2017aug11
https://www.linearmotiontips.com/what-is-a-chopper-drive-for-a-stepper-motor/

(18.4) Optimized Current Control Chopper Modes - Trinamic
https://www.trinamic.com/technology/motor-control-technology/chopper-modes/

(18.5) Trinamic spreadCycle & stealthChop technology for silent stepper motors explained - 2016nov30
https://www.youtube.com/watch?v=Q0sJlGh9WNY&t=18s