@book{21972,
	author = {Darwin, Charles, and Burkhardt, Frederick,},
	title = {Charles Darwin's letters :},
	publisher = {University of Cambridge,},
	year = {1996.},
	address = {Cambridge ;},
	note = {A chart of the Wedgwood and Darwin's family tree on front end papers and a map of the voyage of the Beagle on back end papers.},
	url = {http://www.loc.gov/catdir/description/cam027/95051854.html}
}