^Hancock, David (2001). The mastiffs: the big game hunters, their history, development & future. Ducklington, Oxon: Charwynne Dog Features. ISBN 9780951780114.
^Morris, Desmond (2001). Dogs: the ultimate dictionary of over 1,000 dog breeds. North Pomfret, VT: Trafalgar Square Publishing. pp. 616–617 & 703. ISBN 1-57076-219-8.