APA (7th ed.) Citation

Ordnance Survey. (1961). Great Britain : one inch map, seventh series: One inch map, seventh series. O.S..

Chicago Style (17th ed.) Citation

Ordnance Survey. Great Britain : One Inch Map, Seventh Series: One Inch Map, Seventh Series. O.S., 1961.

MLA (9th ed.) Citation

Ordnance Survey. Great Britain : One Inch Map, Seventh Series: One Inch Map, Seventh Series. O.S., 1961.

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