1. A. Fowler, “Report on Series in Line Spectra.” Fleetway Press, London 1922.
2. Seriengesetz der Linienspectren;Paschen,1922
3. The Structure of Line Spectra;Pauling,1930
4. C. E. Moore, Atomic energy levels Nat. Bur. Stand. (U.S.) Circ. 467, Vol. I (1H-23V) (1949);
5. Vol. II (24Cr-41Nb) (1952);