Wikipedia: Nitrogen - Properties of the element, including its history, applications, and characteristics. ChemicalElements.com: Nitrogen - Basic information, atomic structure, and table of isotopes. It's Elemental: Nitrogen - Basic physical and historical information. Especiál Gas Inc.: Nitrogen - Numeric data, uses, and general information. USGS Minerals Information: Nitrogen - Statistics and information on the worldwide supply, demand, and flow of the element (PDF format). EnvironmentalChemistry.com: Nitrogen - Atomic structure, chemical and physical properties, and table of nuclides. Lenntech: Nitrogen - Physical data, chemical properties, health and environmental effects. WebElements: Nitrogen - Extensive information on history, uses, occurrence, compounds, and properties of the element.