Lau, Charles Q, Alexandra Cronberg, Leenisha Marks, and Ashley Amaya. 2019. “In Search of the Optimal Mode for Mobile Phone Surveys in Developing Countries. A Comparison of IVR, SMS, and CATI in Nigeria”. Survey Research Methods 13 (3):305-18. https://doi.org/10.18148/srm/2019.v13i3.7375.