Karshenboim, Savely G. Laser Spectroscopy, Max Planck Institute of Quantum Optics, Max Planck Society;
Karshenboim, S. G. (2006). Search for a possible variation of the fine structure constant. General Relativity and Gravitation, 38(1), 159-182. doi:10.1007/s10714-005-0215-8.