- The United States and the Metric System (PDF)
- Good Calculators — A collection of really good online calculators for use in every day domestic and commercial use.
- Unit Converter — A wide array of converters and calculators.
- Unit Converter at DigitalDutch.com — Easy to use.
- CSGNetwork Converters and Calculators — they have quite a variety.
A search of the Internet will yield a lot more. Information is to be had in great abundance on this subject.