J. Deli, “Nigroxanthin (3’,4’-Didehydro-β,γ-carotene-3,6’-diol), a New Carotenoid Isolated from Paprika (Capsicum annuum var. longum nigrum)”, Chimia, vol. 48, no. 4, p. 102, Apr. 1994, doi: 10.2533/chimia.1994.102.