@book{4000,
	author = {Bartle, Robert C.},
	title = {Introduction to real analysis},
	publisher = {Pearson Education Publisher},
	address = {New Delhi},
	edition = {3rd},
	url = {https://libgen.is/book/index.php?md5=E62C7697FCF14E44F3E6C3D0FAD27948}
}