FAMILY/ SURNAME, Initials or ISSUING ORGANISATION. (Year of publication – in brackets) Title of map in italics. Sheet number – if available. Scale details. Series – if available. Place of Publication: Publisher.
ORDNANCE SURVEY. (1956) Map of Roman Britain, Scale sixteen miles to one inch. Southampton: Ordnance Survey.
In-text citation example:
(Ordnance Survey, 1956)
As can be seen in the Map of Roman Britain (Ordnance Survey, 1956)