APA (7th ed.) Citation

Marr, J. E. (2013). The Principles of Stratigraphical Geology. Project Gutenberg.

Chicago Style (17th ed.) Citation

Marr, J. E. The Principles of Stratigraphical Geology. Project Gutenberg, 2013.

MLA (9th ed.) Citation

Marr, J. E. The Principles of Stratigraphical Geology. Project Gutenberg, 2013.

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