@book{15814,
	author = {Kreyszig, erwin},
	title = {Introductory functional analysis with application},
	publisher = {John Wiley & Sons Publisher},
	address = {new york},
	url = {https://libgen.is/book/index.php?md5=AE6B02F526AD8B55F32B7A25CF16495A}
}