@article {25235,
	title = {Natural gas, with incidental reference to other bitumens},
	volume = {174},
	year = {1912},
	pages = {477-498},
	publisher = {Journal of the Franklin Institute},
	url = {http://www.plantbiology.siu.edu/faculty/vitt/pdf/161-1997.PDF},
	author = {Knapp, I. N.}
}
