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.].
Lua i Stíl Chicago (17ú heag.)Furtado, Peter, agus Candida Geddes. The Ordnance Survey Guide to Castles in Britain: Ed. by Peter Furtado, Candida Geddes [u.a.]. Southampton: Ornance Survey [u.a.], 1987.
Lua MLA (8ú heag.)Furtado, Peter, agus Candida Geddes. The Ordnance Survey Guide to Castles in Britain: Ed. by Peter Furtado, Candida Geddes [u.a.]. Ornance Survey [u.a.], 1987.
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