George Watson

Girnigoe and Sinclair Castles by Ian Sutherland

Historic Castles and Families in the North by D.B. Miller

History of Caithness by J.T. Calder

Ian Sinclair

Laurel Fechner

Niven Sinclair

Peerage of Scotland by Douglas

Royal Commission on the ancient and historical monuments and constructions of Scotland. Third Report and inventory of Monuments etc. in the County of Caithness.

Sainteclaires of Rosslyn by Father Hay

The Caithness Book edited by Donald Omand

The Castellated and Domestic Architecture of Scotland by McGibbon and Ross

The Fortified House in Scotland by Nigel Tranter

The Orkneyinga Saga by Joseph Anderson

The Scots Peerage edited by Sir James Balfour Paul

The Sinclair Genealogy from "The mists of time" by Niven Sinclair

The St. Clairs of the Isles by Roland William Sinclair

the Sinclair family... timeline