APA (7th ed.) Citation

National Portrait Gallery (Great Britain), Gibson, R., & Simson, J. (1988). The National Portrait Gallery collection. National Portrait Gallery.

Chicago Style (17th ed.) Citation

National Portrait Gallery (Great Britain), Robin Gibson, and Jacob Simson. The National Portrait Gallery Collection. London: National Portrait Gallery, 1988.

MLA (9th ed.) Citation

National Portrait Gallery (Great Britain), et al. The National Portrait Gallery Collection. National Portrait Gallery, 1988.