William de Brit was Sheriff of Connacht until his death at the battle of Termon MacGrath in 1247.

• Knox, Robert Thomas. The History of the County of Mayo to the Close of the Sixteenth Century. With illustrations and three maps. (Originally published c.1890. Castlebourke, De Burca 2000.

• http://www.ucc.ie/celt/published/G100011/index.html