@book{54045,
	author = {Blalock, Hubert M.},
	title = {Introduction to social research /},
	publisher = {Prentice-Hall;},
	year = {1970.},
	series = {Prentice-Hall general sociology series},
	address = {Englewood Cliffs, N.J. :},
	edition = {2nd ed.}
}