@book {554,
	title = {Groups in harmony and tension: an integration of studies on intergroup relations},
	year = {1966},
	publisher = {Octagon Books},
	organization = {Octagon Books},
	url = {https://books.google.com/books?id=uLFkAAAAIAAJ},
	author = {Sherif, M. and Sherif, C.W.}
}
