Clotfelter, Ethan D.; Hollis, Karen L. (May 2008). "Cognition in Domestic Dogs: Object Permanence & Social Cueing". The American Biology Teacher. 70 (5): 293. doi:10.1662/0002-7685(2008)70[293:CIDDOP]2.0.CO;2.
Raber, Hans (1971). Die Schweizer Hunderassen(PDF). p. Chapter 6 (revised) History of the Greater Swiss Mountain Dog. Archived from the original(PDF) on April 28, 2019. Retrieved April 27, 2019.
Raber, Hans (1971). Die Schweizer Hunderassen(PDF). p. Chapter 6 (revised) History of the Greater Swiss Mountain Dog. Archived from the original(PDF) on April 28, 2019. Retrieved April 27, 2019.