@book{21027,
	author = {Oppenheim, Alan V.},
	title = {Signals and systems},
	publisher = {Pearson Education Publisher},
	year = {2007},
	address = {New York},
	edition = {2nd},
	url = {https://libgen.is/book/index.php?md5=7F7AD99407402BBCE00103AFC50DBC22}
}