1. 1. Cochran WG. Sampling techniques: : 3th edition. John Wiley & Sons; New york, 1977. #
2. 2. Narouei M-R, Saadati D, Najimi M, Gangali H, Shah Karami F. Prevalence and risk factors of Brucella infection in sheep and goats in the Sistan region by PCR method. Journal of Zoonotic Diseases. 2022. #
3. 3. Mohammad K, Malekafzali H. Statistical Methods and Health Indices. 19th edition. Jafari Novin; Tehran, 2021. 360 p. #
4. 4. Michael T, Robert C, Helen B, Peter J, Diggle, Nigel F, Keith H, Louise K, Annette O, Jan S, Hannah W. Veterinary Epidemiology: 4th edition. John Wiley & Sons; 2018.#
5. 5. Haghdoost A. Do You Want to Gain a Profound Insight into Sample Size and Statistical Power. Iranian Journal of Epidemiology, 2009;5(1):57-63.#