1. Regionalizing perinatal health services in Massachusetts;Ryan;N. Engl. J. Med.,1977
2. Perinatal intensive care after integration of obstetrical services in Quebec,1973
3. Regionalization of perinatal care in rural areas based on the Iowa experience;Hein;Semin. Perinatol.,1977
4. Regional planning for maternal and perinatal health services;Ryan;Semin. Perinatol.,1977
5. Changing mortality rates with perinatal intensive care and regionalization;Usher;Semin. Perinatol.,1977