Phy.org - Science: Chemistry: Elements: Protactinium

ChemGlobe: Protactinium - Electronic, thermal, and steric data along with an isotope table.
ChemicalElements.com: Protactinium - Basic information, atomic structure, and isotopes.
EnvironmentalChemistry.com: Protactinium - Atomic structure, chemical and physical properties, and table of nuclides.
It's Elemental: Protactinium - Basic physical and historical information.
Visual Elements: Protactinium - General and physical information, source, and key isotopes.
WebElements: Protactinium - Extensive information on history, uses, occurrence, compounds, and properties.

Media publications

Radiochemistry of Protactinium - Full text of the monograph by H. W. Kirby (Mound Laboratory, Miamisburg, Ohio). (Published 1959-12-01 00:00:00)