@book{8990,
	author = {Enderton, Herbert B.},
	title = {A mathematical introduction to logic},
	publisher = {Elsevier},
	year = {2006},
	address = {New Delhi},
	edition = {2nd},
	url = {https://libgen.is/book/index.php?md5=40C950B41471307C070C3E141FC9E1A2}
}