@article {5394,
	title = {Estimating the Impact of Impaired Visibility on the Demand for Visits to National Parks},
	journal = {Tourism Economics},
	volume = {19},
	year = {2013},
	month = {April},
	pages = {433-452},
	keywords = {Air pollution, Tourism, Visibility},
	author = {Poudyal, Neelam C and Paudel, Bamadev and Green, Gary T}
}
