- The Planimeter Applet - demonstrates the planimeter, the geometric areas it measures, and the planimeter's wheel reading as the user traces a number of samples and the applet allows the simulated planimeter's dimensions to be altered and measurements scaled.
- The Planimeter Applet Guide - describes the planimeter mechanically and mathematically, and the use of the applet.
- The Polar Planimeter - a book by J. Y. Wheatley, 1903, describes the real instrument and how it was used.
- If you want to take the applet home with you, you need the applet's page (or something like it), the applet executable, and maybe the map also (but it's huge and wants to be in a subdirectory named "data"). And you can have the applet source too, no charge.

- Planimeters at the Museum of HP Calculators - some description and photographs (and other cool stuff)
- ASC Scientific, Ben Meadows Company and Sokkia Corporation - sell mostly digital planimeters
- Lasico - sells a variety of planimeters and related instruments
- Planimeter in Kunkel's Mathematics Lessons - detailed description and explanation
- Area Measurement: Planimeters & Green's Theorem - area mathematics for rolling planimeters
- The Incredible Inedible Planimeter - mathematics with excellent drawings, and that darn Green's Theorem
- Planimeters - very accessible descriptions, and links

Larry Leinweber, Proprietor