К2
M83	Morre, E. By     Atomic energy levels. As Derived From the Analyses of Optical Spectra [Текст]. The Spectra of Chromium, Manganese, Iron, Cobalt, Nickel, Copper, Zinc, Gallium, Germanium, Arsenic, Selenium, Bromine, Krypton, Rubidium, Strontium, Yttrium, Zirconium, and Niobium / United states department of commerce, Cherles Sawyer, Secretary.National bureau of standards, E. U. Condon, Director. — 1952. — 309 p.