@book{19315,
	author = {Twenhofel, William H. and Shrock, Robert R.},
	title = {Principles of invertebrate paleontology},
	publisher = {McGraw-Hill,},
	year = {1953.},
	series = {McGraw-Hill series in geology},
	address = {New York,},
	edition = {2d ed.},
	note = {"A revised and enlarged edition of Twenhofel and Shrock, Invertebrate paleontology."}
}