Samir, F., R.F.E. Naggar, M.M. Hamoud, M.M. Zaki, A.M. Gamal, S.E. Laban, S.A.E. Nasr, E. Ismael and O.K. Zahran. 2018. Persistence of newcastle disease virus genotype ii and shedded genotype vii in poultry farm environment. Hosts and Viruses, 5(6): 81-90.