1. WHO, UNICEF, World Bank. State of the world’s vaccines and immunization. Geneva: World Health Organization; 2009.
2. WHO. Fact sheets—immunization coverage 2019. https://www.who.int/news-room/fact-sheets/detail/immunization-coverage. Accessed 27 Oct 2020.
3. National Population Commission (NPC) [Nigeria] and ICF. 2019. Nigeria Demographic and Health Survey 2018. Abuja, Nigeria, and Rockville, Maryland, USA: NPC and ICF.
4. Reason P, Bradbury H, editors. The Sage handbook of action research: participative inquiry and practice. Sage, CA; 2008. ISBN 978–1412920292.
5. Lewin K. Action research and minority problems. J Soc Issues. 1946;2(4):34–46.