APA (7th ed.) Citation

De Boer, G., & Skelton, R. A. (1969). The earliest English chart with soundings.

Chicago Style (17th ed.) Citation

De Boer, G., and R. A. Skelton. The Earliest English Chart with Soundings. 1969.

MLA (9th ed.) Citation

De Boer, G., and R. A. Skelton. The Earliest English Chart with Soundings. 1969.

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