Informal payments for maternity health services in public hospitals in Greece - Kaitelidou, Daphne Ch; Tsirona, Christina S; Galanis, Petros A; Siskou, Olga Ch; Mladovsky, Philipa; Kouli, Eugenia G; Prezerakos, Panagiotis E; Theodorou, Mamas; Sourtzi, Panagiota A; Liaropoulos, Lykourgos L (Health policy, 2013)