1. Sheep: Their Breeds, Management, and Diseases: To Which Is Added the Mountain Shepherd’s Manual;Youatt,1837
2. The history of sheep breeds in Britain;Ryder;Agric. Hist. Rev.,1964
3. A survey of European primitive breeds of sheep
4. World Watch List for Domestic Animal Diversity,2000
5. Shaggy sheep stories;Green;Ctry. Life,2017