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Lundgren, Anders (1988). "The New Chemistry in Sweden: The Debate That Wasn't". Osiris4 The Chemical Revolution: Essays in Reinterpretation: 146–168. doi:10.1086/368676.
"The Discovery of the Elements: VII. Columbium, Tantalum, and Vanadium". Journal of Chemical Education9 (5): 863–884. 1932. doi:10.1021/ed009p863. Bibcode: 1932JChEd...9..863W. - subscription required