Symonds, R.C. et al. (2007): Carotenoids in the sea urchin Paracentrotus lividus: occurrence of 9'-cis-echinenone as the dominant carotenoid in gonad colour determination. In: Comp. Biochem. Physiol. B, Biochem. Mol. Biol. 148, 432–444. doi:10.1016/j.cbpb.2007.07.012.
