Pap smear coverage and factors associated with non-participation in cervical cancer screening: an analysis of the Cervical Cancer Prevention Program in Pernambuco State, Brazil - Albuquerque, K M; Frias, P G; Andrade, C LT; Aquino, E ML; Menezes, G; Szwarcwald, C L (Cad Saude Publica, 2009)