Karshenboim, Savely G. Laser Spectroscopy, Max Planck Institute of Quantum Optics, Max Planck Society;
Karshenboim, S. G., & Ivanov, V. G. (2008). Nonresonant Effects and Hydrogen Transition Line Shape in Cosmological Recombination Problems. Astronomy Letters, 34(5), 289-297. doi:10.1134/S1063773708050010.