W. HANLE and H. KLEINPOPPEN In 1919, in the first edition of Atombau and Spektrallinien, Sommerfeld referred to the immense amount of information which had been accumu lated during the first period of 60 years of spectroscopic practice. Sommer feld emphasized that the names of Planck and Bohr would be connected forever with the efforts that had been made to understand the physics and the theory of spectral lines. Another period of almost 60 years has elapsed since the first edition of Sommerfeld's famous monograph. As the editors of this monograph, Progress in Atomic Spectroscopy, we feel...

W. HANLE and H. KLEINPOPPEN In 1919, in the first edition of Atombau and Spektrallinien, Sommerfeld referred to the immense amount of information which had been accumu lated during the first period of 60 years of spectroscopic practice. Sommer feld emphasized that the names of Planck and Bohr would be connected forever with the efforts that had been made to understand the physics and the theory of spectral lines. Another period of almost 60 years has elapsed since the first edition of Sommerfeld's famous monograph. As the editors of this monograph, Progress in Atomic Spectroscopy, we feel...