Reference

Tinkering Studio Circuit Boards

Tinkering Studio Toy Deconstruction

Pacific Science Center Tinker Tank

Paper:Bits

Instructables - Build a Simple Circuit From a Pizza Box

Encyclopedia of Electronic Components vol 1,2,3

little Bits color convention

microcontroller input protection techniques

T³: Using LEDs as Light Sensors

Relay switch circuit

Simplest Method to Make a Motor Turn Off, Turn On, Go Forwards, and Go Backwards

How to make Magnetic Battery Connectors