Britannica Nobel Prize: Krypton: Overview and basic data.
ChemGlobe: Krypton: Electronic, thermal, and steric data along with an isotope table.
Chemical Elements.com: Krypton: Basic information, atomic structure, and table of isotopes.
EnvironmentalChemistry.com: Krypton: Atomic structure, properties, and table of nuclides.
Especiál Gas Inc.: Krypton: Numeric data, uses, and general information.
It's Elemental: Krypton: Basic physical and historical information.
Krypton: Data tables and historic information.
LANL: Krypton: History, sources, isotopes, and uses.
Lenntech: Krypton: Physical data, chemical properties, health and environmental effects.
Visual Elements: Krypton: General and physical information, uses, key isotopes, and ionisation energies.
WebElements: Krypton: Extensive information on history, uses, occurrence, compounds, and properties of the element.
What Does the Element Krypton Look Like?: Explanation with photographs.
Wikipedia: Krypton: Properties of the element, including its history, applications, and characteristics.