‎"ÅNGSTRÖM, A.J. et T.R. THALÉN.‎
‎Recherches sur les spectres métalloïdes. Avec deux Planches.‎

‎Upsala, Berling, 1875. Uncut in original printed wrappers. The entire volume of ""Nova Acta Regiæ Societatis Scient. Upsaliensis."" Seriei Tertiæ. Vol. IX, Fasc. II. The memoir: 34 pp. and 2 large folded plates.‎

Reference : 59142

‎First printing.""A work on the spectra of the metalliods, which was begun some years previously, was completed by Tobias Robert Thalén, who actively assisted Ångström for many years, and was published in 1875. In opposition to the view that a given chemical element had a multiplicity of spectra, depending upon conditions, Ångström remained a strong defender of the opinion that each chemical element had a single characteristic spectrum that remained essentially unchanged."" (DSB).‎