Não informado. (2001). Pig improvement services. Meat and Livestock Commission.
Chicago-Zitierstil (17. Ausg.)Não informado. Pig Improvement Services. Bletchley, Inglaterra: Meat and Livestock Commission, 2001.
MLA-Zitierstil (8. Ausg.)Não informado. Pig Improvement Services. Meat and Livestock Commission, 2001.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.