Gabrielse, G.; Khabbaz, A.; Hall, D. S.; Heimann, C.; Kalinowsky, H.; Jhe, W. (1999-04-19). "Precision Mass Spectroscopy of the Antiproton and Proton Using Simultaneously Trapped Particles". Physical Review Letters. 82 (16): 3198–3201. Bibcode:1999PhRvL..82.3198G. doi:10.1103/PhysRevLett.82.3198.
Gabrielse, G.; Khabbaz, A.; Hall, D. S.; Heimann, C.; Kalinowsky, H.; Jhe, W. (1999-04-19). "Precision Mass Spectroscopy of the Antiproton and Proton Using Simultaneously Trapped Particles". Physical Review Letters. 82 (16): 3198–3201. Bibcode:1999PhRvL..82.3198G. doi:10.1103/PhysRevLett.82.3198.