Jensen, William B. (1982). "The Positions of Lanthanum (Actinium) and Lutetium (Lawrencium) in the Periodic Table". Journal of Chemical Education. 59 (8): 634–636. Bibcode:1982JChEd..59..634J. doi:10.1021/ed059p634.
Jensen, William B. (1982). "The Positions of Lanthanum (Actinium) and Lutetium (Lawrencium) in the Periodic Table". Journal of Chemical Education. 59 (8): 634–636. Bibcode:1982JChEd..59..634J. doi:10.1021/ed059p634.