APA (7th ed.) Citation

Haeckel, E. (2005). Monism as Connecting Religion and Science A Man of Science. Project Gutenberg.

Chicago Style (17th ed.) Citation

Haeckel, Ernst. Monism as Connecting Religion and Science A Man of Science. Project Gutenberg, 2005.

MLA (9th ed.) Citation

Haeckel, Ernst. Monism as Connecting Religion and Science A Man of Science. Project Gutenberg, 2005.

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