Lawal, J.R., et al. “Prevalence of Infectious Bursal Disease (Gumboro) Antibodies in Village Chickens in Gombe State, Northeastern Nigeria”. International Journal of Poultry Science, vol. 13, no. 12, Nov. 2014, pp. 703–708, https://doi.org/10.3923/ijps.2014.703.708.