In the last ten years a great deal of work has been done on the experimental investigation of atomic energy levels using magnetic resonance techniques. This paper concerns itself primarily with a review of some of the studies of atomic vapors in connection with level structures, on the one hand, and the mutual interactions of light oscillating magnetic fields and the effects of collisions, on the other.
F. Bitter, "Magnetic Resonance in Radiating or Absorbing Atoms," Appl. Opt. 1, 1-10 (1962)