Furtado, P., & Geddes, C. (1987). The Ordnance Survey guide to Castles in Britain: Ed. by Peter Furtado, Candida Geddes [u.a.]. Ornance Survey [u.a.].

Furtado, Peter, and Candida Geddes. The Ordnance Survey Guide to Castles in Britain: Ed. by Peter Furtado, Candida Geddes [u.a.]. Southampton: Ornance Survey [u.a.], 1987.

Furtado, Peter, and Candida Geddes. The Ordnance Survey Guide to Castles in Britain: Ed. by Peter Furtado, Candida Geddes [u.a.]. Ornance Survey [u.a.], 1987.