Wyatt, M., Shao, Z., Stein, B. K., & Brenton, A. G. (2010). Accurate mass measurement by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. II. Measurement of negative radical ions using porphyrin and fullerene standard reference materials. Rapid Communications in Mass Spectrometry, 24(20), pp. 3052-3056. doi:10.1002/rcm.4725

Wyatt, Mark, Zhecheng Shao, Bridget K. Stein, and A. Gareth Brenton. "Accurate Mass Measurement By Matrix-assisted Laser Desorption/ionisation Time-of-flight Mass Spectrometry. II. Measurement of Negative Radical Ions Using Porphyrin and Fullerene Standard Reference Materials." Rapid Communications in Mass Spectrometry 24, no. 20 (2010): 3052-3056.

Wyatt, Mark, Zhecheng Shao, Bridget K. Stein, and A. Gareth Brenton. "Accurate Mass Measurement By Matrix-assisted Laser Desorption/ionisation Time-of-flight Mass Spectrometry. II. Measurement of Negative Radical Ions Using Porphyrin and Fullerene Standard Reference Materials." Rapid Communications in Mass Spectrometry 24.20 (2010): 3052-3056.