@article{Stouf40,
	author = {Stouffer, Samuel A.},
	journal = {American Sociological Review},
	number = {6},
	pages = {845--867},
	title = {Intervening Opportunities: A Theory Relating Mobility and Distance},
	volume = {5},
	year = {1940}
}

@article{Tobl70,
	author = {Tobler, Waldo},
	journal = {Economic Geography},
	number = {2},
	pages = {234--240},
	title = {A computer movie simulating urban growth in the Detroit region},
	volume = {46},
	year = {1970}
}

@book{Reill31,
	author = {Reilly, William},
	location = {New York},
	publisher = {Knickerbocker Press},
	title = {The law of retail gravitation},
	year = {1931}
}

@article{Wils71,
	author = {Wilson, A.G.},
	journal = {Environment and Planning},
	pages = {1-31},
	publisher = {Pion},
	title = {A family of spatial interaction models, and associated developments},
	year = {1971},
	volume = {3}
}

