APA (7th ed.) Citation

(1903). The most important thing in the world. A lecture delivered in [...] Glasgow. "Sentinel" Office etc..

Chicago Style (17th ed.) Citation

The Most Important Thing in the World. A Lecture Delivered in [...] Glasgow. "Sentinel" Office etc., 1903.

MLA (8th ed.) Citation

The Most Important Thing in the World. A Lecture Delivered in [...] Glasgow. "Sentinel" Office etc., 1903.

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