APA (7th ed.) Citation

Great Britain. Ordnance Survey. (1970). [Planning maps of London]. [Ordnance Survey?].

Chicago Style (17th ed.) Citation

Great Britain. Ordnance Survey. [Planning Maps of London]. [England?]: [Ordnance Survey?], 1970.

MLA (8th ed.) Citation

Great Britain. Ordnance Survey. [Planning Maps of London]. [Ordnance Survey?], 1970.

Warning: These citations may not always be 100% accurate.