G. Drake, Atomic, Molecular, and Optical Physics.  (American Institute of Physics, New York, 1996).

R. Cowan, The Theory of Atomic Structure and Spectra.  (University of California Press, London, 1981).

http://webphysics.davidson.edu/Alumni/BeDenius/rubidium/results.html

http://physics.nist.gov/cgi-bin/AtData/main_asd

contemplating the awesome power of lasers