Ademola K (Nov.13, 2016). Problem – Based Instructional Strategy and Numerical Ability as Determinants of Senior Secondary Achievement in Mathematics. Journal of Education and PracticeISSN 2222-1735 (Paper) ISSN 2222-288X (Online)Vol.7, No.13, 2016. Retrieved from the website www.iiste.org.
Adesoji, A. Francis. (2008). Students Ability Levels and Effectiveness of Problem-Solving Strategy. J. Soc. Sci., 17(1): 5-8 (2008) Retrieved from the website francisadesoji@yahoo.com.