Anderson, Joseph (ed.) (1873) The Orkneyinga Saga. Translated by Jón A. Hjaltalin & Gilbert Goudie. Edinburgh. Edmonston and Douglas. The Internet Archive. Retrieved 26 August 2013.
See Bringing Colour to the Shetland Isles, by Gerry L Sanderson, 1976, page 48, available on-line hereArchived 25 September 2006 at the Wayback Machine.
Okill, David; Shaw, Deryk (2010). "Fair Isle". In Archer, Mike; Grantham, Mark; Howlett, Peter; Stansfield, Steven (eds.). Bird Observatories of Britain and Ireland(PDF). T & A D Poyser. Archived from the original(PDF) on 24 March 2012.
See Bringing Colour to the Shetland Isles, by Gerry L Sanderson, 1976, page 48, available on-line hereArchived 25 September 2006 at the Wayback Machine.
Okill, David; Shaw, Deryk (2010). "Fair Isle". In Archer, Mike; Grantham, Mark; Howlett, Peter; Stansfield, Steven (eds.). Bird Observatories of Britain and Ireland(PDF). T & A D Poyser. Archived from the original(PDF) on 24 March 2012.