@book{30374,
	author = {Prior, A. N.},
	title = {Formal logic /},
	publisher = {Clarendon,},
	year = {c1962.},
	address = {Oxford :},
	edition = {2nd ed.},
	url = {http://dx.doi.org/10.1093/acprof:oso/9780198241560.001.0001}
}