@book{11221,
	author = {Grimaldi, Ralph P},
	title = {Discrete and combinatorial mathematics},
	publisher = {Pearson Education Publisher},
	address = {New Dehli},
	edition = {6th},
	url = {https://libgen.is/book/index.php?md5=E45052764212FCAE4D91BC85FEA97ACB}
}