Naď, Pavel, et al. “Effect of Dietary Supplementation of Humic Substances on Production Performance and Slaughter Value of Broiler Chicken”. Animal Welfare, Ethology and Housing Systems (AWETH), vol. 16, no. 2, Dec. 2020, pp. 156-62, https://doi.org/10.17205/SZIE.AWETH.2020.2.156.