@book{47080,
	author = {Nesbet, R. K. and ebrary, Inc.},
	title = {Variational principles and methods in theoretical physics and chemistry},
	publisher = {Cambridge University Press,},
	year = {2003.},
	address = {New York :},
	url = {http://site.ebrary.com/lib/rucke/Doc?id=10062686}
}