SINGH, D B, et al. “Variation in Chlorophyll and Carotenoid Contents in Kale (Brassica Oleracea) As Influenced by Cultivars and Harvesting Dates”. The Indian Journal of Agricultural Sciences, vol. 84, no. 10, Oct. 2014, pp. 1178–81, https://doi.org/10.56093/ijas.v84i10.44123.