APA (7th ed.) Citation

Semmes, D. R. (1919). The geology of the San Juan district, Porto Rico. New York Academy of Sciences.

Chicago Style (17th ed.) Citation

Semmes, Douglas Ramsay. The Geology of the San Juan District, Porto Rico. New York: New York Academy of Sciences, 1919.

MLA (9th ed.) Citation

Semmes, Douglas Ramsay. The Geology of the San Juan District, Porto Rico. New York Academy of Sciences, 1919.

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