1. The positions of lanthanum (actinium) and lutetium (lawrencium) in the periodic table
2. Provisional Report on Discussions on Group 3 of The Periodic Table
3. The location and composition of Group 3 of the periodic table
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5. E.Scerri , The Impact of Twentieth-Century Physics on the Periodic Table and Some Remaining Questions in the Twenty-First Century , in 150 Years of the Periodic Table, Perspectives on the History of Chemistry , ed. C. J. Giunta et al. , Springer , Switzerland , 2012 , pp. 409–423