Baker, C., Ahmadi, M., Alves, B. X. R., Bertsche, W., Butler, E., Capra, A., . . . Wurtele, J. S. (2016). Observation of the 1S–2S transition in trapped antihydrogen. Nature, 541(7638), pp. 506-510. doi:10.1038/nature21040

Baker, Christopher, et al. "Observation of the 1S–2S Transition in Trapped Antihydrogen." Nature 541, no. 7638 (2016): 506-510.

Baker, Christopher, et al. "Observation of the 1S–2S Transition in Trapped Antihydrogen." Nature 541.7638 (2016): 506-510.