C. F.  Summers and Harwood, J., ?The Grey seal ?problem? in the Outer Hebrides?, Proc. R. Soc. Edinburgh. Sect. B. Biol. Sci., vol. 77, pp. 495?503, 2011.

C.  Duck, Morris, C., and Unit, N. E. R. C. Sea Mammal, ?Surveys of harbour (common) and grey seals in the Outer Hebrides and the Moray Firth in August 2011?, 518, 2012.