Reference Label	Details
Bergeson 1998	S. D. Bergeson, A. Balakrishnan, K. G. H. Baldwin, T. B. Lucatorto, J. P. Marangos, T. J. McIlrath, T. R. O'Brian, S. L. Rolston, C. J. Sansonetti, J. Wen, and N. Westbrook. Phys. Rev. Lett. 80, 3475-3478 (1998) Measurement of the He Ground State Lamb Shift via the Two-Photon 1 1S - 2 1S Transition