Khattab, Adel Salah, et al. “A Comparison Between Different Selection Indexes for Milk and Udder Health Traits on Holstein-Friesian Cows in Egypt”. Animal Welfare, Ethology and Housing Systems (AWETH), vol. 17, no. 1, June 2021, pp. 42-50, https://doi.org/10.17205/SZIE.AWETH.2021.1.042.