Constantes físicas

• LEVEL 5 Physical Constants
• LEVEL 5 "Best" Cosmological Parameters
• WMAP Cosmological Parameters Model/Dataset Matrix
• CODATA Internationally recommended values of the Fundamental Physical Constants at NIST
• NIST Physical Reference Data
• Particle Properties Database (PDG)

Unidades

• System of Units (SI) at VizieR
• International System of Units (SI) at NIST
• Fundamental Astronomical Conversions

Tablas periódicas

• Periodic Table of the Elements
• WebElements Periodic Table

Calculadoras

• Martindale's Physics Calculators
• Ned Wright's Javascript Cosmology Calculator
• Absorption Law Calculator
• Conversion of Units

Sistemas fotométricos

• The Asiago Database on Photometric Systems (ADPS)
• The Lausanne Photometric Database (GCPD)