1. NAHMS. Sheep 2001 Part II: Reference of Sheep Health in the United States 2001. 2003. Available at: http://www.aphis.usda.gov/vs/ceah/ncahs/nahms/sheep/sheep01/sheep01Pt2.pdf)\. Accessed May 1, 2006.
2. Trichostrongyles;Levine,1980
3. Population dynamics of Haemonchus contortus and Trichostrongylus spp in sheep;Courtney;Int J Parasitol,1983
4. Nematodes of the gastrointestinal tract;Soulsby,1965
5. Anthelmintic resistance of gastrointestinal parasites in small ruminants;Fleming;J Vet Intern Med,2006