N.S. Mumthas, and Shyma Usman Abdulla. “Substandard Performance in Mathematical Problem Solving in Physics Among Higher Secondary School Students in Kerala - An Investigation on Teacher Perceptions and Student Difficulties”. Issues and Ideas in Education, vol. 7, no. 1, Mar. 2019, pp. 35-43, doi:10.15415/iie.2019.71005.