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Yusoff, Khatijah, Wen Siang Tan, Chin Hoon Lau, Ban Kim Ng, and Abdul Latif Ibrahim. Sequence of the Haemagglutinin-neuraminidase Gene of the Newcastle Disease Virus Oral Vaccine Strain V4(UPM). Houghton Trust, 1996.

Yusoff, Khatijah, et al. Sequence of the Haemagglutinin-neuraminidase Gene of the Newcastle Disease Virus Oral Vaccine Strain V4(UPM). Houghton Trust, 1996.