Regmi, P. R., E. Waithaka, A. Paudyal, P. Simkhada, and E. van Teijlingen. “Guide to the Design and Application of Online Questionnaire Surveys”. Nepal Journal of Epidemiology, vol. 6, no. 4, May 2017, pp. 640-4, doi:10.3126/nje.v6i4.17258.