Quest for knowledge

One year ago I picked up an online resource called "Jones on Stepper
Motors". It was an introduction to steppers and how they work etc.
Now that I have built some stepper systems I want to go to the next
level. I am looking for the same type of introductory text on servo
motors and controls. Can someone point me to a "Jones on Servo Motors",
"Servos for Dummies", etc.?