2Kennedy T J ,Bruer D J ,Marchiondo A A. Prevalence of swine parasites in major hog producing area of the United States [J]. Agri Praet, 1988 (5) : 445 -500.
3Anderson T J C ,Komuniecki R ,Komuniecki P R. Aremitochondria inherited paternally in Ascaris [J].Int J Parasitol, 1993,25(8) : 1001-1004.
4Peng W ,Anderson TJ,Zho. X ,et al. Genetic variation in sympat tic Ascaris populations from humans and pigs in China [J ]. Parasitology, 1998,117 : 355-361.