1. Alvi, M. (2016). A manual for selecting sampling techniques in research. University of Karachi, Iqra University.
2. Anum, G. (2017). Research instruments for data collection. Department of Fine Art and Media Art Technology, Kwame Nkrumah University of Science and Technology
3. Arthur-Nyarko, E. (2017). Learner characteristics and responsiveness to e-learning delivery in selected distance education institutions in Ghana (unpublished PhD Thesis). Department of Educational Communication Technology, Kenyatta University.
4. Creswell, J. W. (2014). Research design, qualitative, quantitative and mixed method approaches (4th ed.). SAGE Publication.
5. Israel, G.D. (1992) Determining Sample Size. University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS, Florida.