Sahar, M.O., et al. “Residual Pathogenic Effects of Infectious Bursal Disease Vaccines Containing Intermediate and Hot Strains of the Virus in Broiler Chickens”. International Journal of Poultry Science, vol. 3, no. 6, May 2004, pp. 415–418, https://doi.org/10.3923/ijps.2004.415.418.