APA (7th ed.) Citation

Haeckel, E. Last Words on Evolution: A Popular Retrospect and Summary.

Chicago Style (17th ed.) Citation

Haeckel, Ernst. Last Words on Evolution: A Popular Retrospect and Summary.

MLA (9th ed.) Citation

Haeckel, Ernst. Last Words on Evolution: A Popular Retrospect and Summary.

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