@book{38048,
	author = {Singer, Judith D. and Willett, John B.},
	title = {Applied longitudinal data analysis},
	publisher = {Oxford University Press,},
	year = {2003.},
	address = {New York ;},
	url = {http://dx.doi.org/10.1093/acprof:oso/9780195152968.001.0001}
}