Dewi, N. W. E. P., Sawitri, A. A. S., & Muliawan, P. (2019). The effectiveness of WhatsApp video to increase knowledge of pneumonia early detection among mothers of children under five years. Public Health and Preventive Medicine Archive, 7(1), 60–65. https://doi.org/10.53638/phpma.2019.v7.i1.p12