Wyatt, M., Griffiths, N. W., Kean, S. D., Graham, A. E., Stein, B. K., & Brenton, A. G. (2010). Accurate mass measurement by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. I. Measurement of positive radical ions using porphyrin standard reference materials. Rapid Communications in Mass Spectrometry, 24(11), pp. 1629-1635. doi:10.1002/rcm.4560

Wyatt, Mark, Nia W. Griffiths, Suzanna D. Kean, Andrew E. Graham, Bridget K. Stein, and A. Gareth Brenton. "Accurate Mass Measurement By Matrix-assisted Laser Desorption/ionisation Time-of-flight Mass Spectrometry. I. Measurement of Positive Radical Ions Using Porphyrin Standard Reference Materials." Rapid Communications in Mass Spectrometry 24, no. 11 (2010): 1629-1635.

Wyatt, Mark, et al. "Accurate Mass Measurement By Matrix-assisted Laser Desorption/ionisation Time-of-flight Mass Spectrometry. I. Measurement of Positive Radical Ions Using Porphyrin Standard Reference Materials." Rapid Communications in Mass Spectrometry 24.11 (2010): 1629-1635.