Yahya, D. O., and S. T. Adebola. “Availability of Activities and Appropriateness of Graphical Illustrations in Recommended Economics Textbooks for Senior Secondary School Students in Ogun State, Nigeria”. The International Journal of Humanities & Social Studies, vol. 7, no. 4, Apr. 2019, doi:10.24940/theijhss/2019/v7/i4/HS1904-037.