APA (7th ed.) Citation

Merck and Co. (2012). Merck's 1899 Manual. Project Gutenberg.

Chicago Style (17th ed.) Citation

Merck and Co. Merck's 1899 Manual. Project Gutenberg, 2012.

MLA (9th ed.) Citation

Merck and Co. Merck's 1899 Manual. Project Gutenberg, 2012.

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