ChemGlobe: Dubnium: Electronic data along with an isotope table and basic facts.
ChemicalElements.com: Dubnium: Diagram of its atomic structure, and basic information.
Dubnium: Historic information.
EnvironmentalChemistry.com: Dubnium: Atomic structure, physical properties, and table of nuclides.
It's Elemental: Dubnium: Basic physical and historical information.
LANL: Dubnium: Basic information, history, and isotopes.
Lenntech: Dubnium: Physical data and chemical properties.
Visual Elements: Dubnium: Image, general and physical information, and key isotopes.
WebElements: Dubnium: Information on history, isolation, and properties.