APA (7th ed.) Citation

Simpson, W. D. (1959). Scottish castles: An introduction to the castles of Scotland (4th impr.). HMSO.

Chicago Style (17th ed.) Citation

Simpson, William Douglas. Scottish Castles: An Introduction to the Castles of Scotland. 4th impr. Edinburgh: HMSO, 1959.

MLA (9th ed.) Citation

Simpson, William Douglas. Scottish Castles: An Introduction to the Castles of Scotland. 4th impr. HMSO, 1959.