Fedotov A M, Narozhny N B Extreme Light Infrastructure: Report on the Grand Challenges Meeting, 27 - 28 April 2009, Paris (Eds G Korn, P Antici) (Paris: Extreme Light Infrastructure, 2009) p. 17
Sommerfeld A Atombau Und Spektrallinien Vol. 2 (Braunschweig: F. Vieweg, 1951); Sommerfeld A Atomic Structure And Spectral Lines (London: Methuen, 1934); Zommerfel’d A Stroenie Atoma i Spektry Vol. 2 (M.: Gostekhizdat, 1956)