Vui, T. Q.; Lohr, J.; Kyule, M.; Zessin, K.-H.; Baumann, M. Antibody Levels Against Newcastle Disease Virus, Infectious Bursal Disease Virus and Avian Influenza Virus in Rural Chickens in Viet Nam. Int. J. Poult. Sci. 2002, 1 (5), 127–132. https://doi.org/10.3923/ijps.2002.127.132.