Weiss, David, van der Luit, Arnold H., Kroon, Johan T.M., Mol, Joseph N.M., Kooter, Jan M., "The petunia homologue of the Antirrhinum majus candi and Zea mays A2 flavonoid genes; homology to flavanone 3-hydroxylase and ethylene-forming enzyme", Plant Molecular Biology, 1993