Cost Effectiveness of Mobile Health for Antenatal Care and Facility Births in Nigeria oleh Diana M. Bowser, Donald S. Shepard, Allyala Nandakumar, Adeyemi Okunogbe, Tyler Morrill, Yara Halasa-Rappell, Monica Jordan, Farida Mushi, Carolyn Boyce, Oluwayemisi A. Erhunmwunse