R. R. Pushpa, J. J. Kirubaharan, and A. Koteeswaran, “Phylogenetic Analysis of the Nucleoprotein Gene of Newcastle Disease Vaccine Viruses in India”, Int. J. Poult. Sci., vol. 8, no. 12, pp. 1137–1150, Nov. 2009, doi: 10.3923/ijps.2009.1137.1150.