American Association of Physics Teachers
Com Padre Digital Library: Open Source Physics: Two Springs and a Pendulum Model
Swing virtual pendulums and compare the motion of one oscillating weight on a horizontal spring to a second weight on another spring. Then, compare how these motions differ from the motion of a simple pendulum.
Wolfram Research
Wolfram Science World: Huygens, Christiaan
This ScienceWorld site provides a short biographical sketch of Christiaan Huygens and describes his most notable scientific discoveries and contributions. Links are provided throughout for additional information as well.