APA (7th ed.) Citation

Webster, R. (1980). The Gemmologist's compendium (6th edition.). NAG Press.

Chicago Style (17th ed.) Citation

Webster, Robert. The Gemmologist's Compendium. 6th edition. London: NAG Press, 1980.

MLA (9th ed.) Citation

Webster, Robert. The Gemmologist's Compendium. 6th edition. NAG Press, 1980.

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