APA (7th ed.) Citation

Porter, H., & Roberts, G. E. (2014). Cups and their Customs. Project Gutenberg.

Chicago Style (17th ed.) Citation

Porter, Henry, and George Edwin Roberts. Cups and Their Customs. Project Gutenberg, 2014.

MLA (9th ed.) Citation

Porter, Henry, and George Edwin Roberts. Cups and Their Customs. Project Gutenberg, 2014.

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