Niizu, P.Y. & Rodriguez-Amaya, Delia B. (2005). "Flowers and Leaves of Tropaeolum majus L. as Rich Sources of Lutein". Journal of Food Science. 70 (9): S605 –S609. doi:10.1111/j.1365-2621.2005.tb08336.x. ISSN1750-3841.
Niizu, P.Y. & Rodriguez-Amaya, Delia B. (2005). "Flowers and Leaves of Tropaeolum majus L. as Rich Sources of Lutein". Journal of Food Science. 70 (9): S605 –S609. doi:10.1111/j.1365-2621.2005.tb08336.x. ISSN1750-3841.