^Suzuki, Y., Doi, M. and Shioi, Y. (2002). “Two enzymatic reaction pathways in the formation of pyropheophorbide a”. Photosynth. Res.74: 225–233. PMID16228561.
^Suzuki, Y., Amano, T. and Shioi, Y. (2006). “Characterization and cloning of the chlorophyll-degrading enzyme pheophorbidase from cotyledons of radish”. Plant Physiol.140: 716–725. PMID16384908.
^Hörtensteiner, S. (2006). “Chlorophyll degradation during senescence”. Annu. Rev. Plant Biol.57: 55–77. PMID16669755.