APA (7th ed.) Citation

Richards, H. G. (1956). Geology of the Delaware Valley. Mineralogical Society of Pennsylvania.

Chicago Style (17th ed.) Citation

Richards, Horace Gardiner. Geology of the Delaware Valley. Philadelphia: Mineralogical Society of Pennsylvania, 1956.

MLA (9th ed.) Citation

Richards, Horace Gardiner. Geology of the Delaware Valley. Mineralogical Society of Pennsylvania, 1956.

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