Standards
Computing, Electrical Engineering, Environmental Practice, Individual Standards, Internet, Organizations, Quality, Standard Document Vendors, Telecommunications, NSSN: A National Resource for Global Standards
Units of Measurement
Online Calculators, Software, All Measures, Anglo-Saxon Weights & Measures, British Weights and Measures Association (BWMA), Conversion Tables, English Weights and Measures, How Many?, IEER Technical Classroom, International System of Units, Metric 4 US, Metric Conversion Tables
Astronomical Constants from NASA
Astronomical/space constants and equations.
Beta-Theta
Gives general defintions, background and examples from the science fields of biology, physics, chemistry, math, and history. Includes forum boards.
EquationSheet.com
Searchable directory, arranged by field, of equations, constants, symbols and SI units. Also features LaTEX utilities, software links.
GrayLIT Network
Searchable database for reports that are generated by federally funded projects.
Physics and Science Reference by PhysLINK.com
Includes physical constants, online unit conversions, periodic table of elements, exact time, fundamental physical formulae and equations.
RefScout
A weekly, scientific reference mailing service. Screens databases covering life and medical sciences for the key words or the combination of key words specified and will automatically update with any abstract that has come up during the last seven days. Free service.
The Constants and Equations Pages
Expanding reference resource for science, math and astronomy