@book{15816,
	author = {Kreyszig,Erwin},
	title = {Introductory Funcational Analysis With Applications},
	publisher = {John Wiley & Sons Publisher},
	year = {2004},
	address = {New York},
	url = {https://libgen.is/book/index.php?md5=AE6B02F526AD8B55F32B7A25CF16495A}
}