@book{165,
	author = {Tocci, Ronald J. and Widmer, Neal S.},
	title = {Digital systems :},
	publisher = {Prentice Hall,},
	year = {2011.},
	address = {Upper Saddle River :},
	edition = {11th ed.},
	url = {https://books.google.com.pk/books?id=0xnvRAAACAAJ&dq=9780135103821&hl=en&sa=X&redir_esc=y}
}