1
Croft T, Davison R. Foundation maths. Seventh edition. Harlow, England: : Pearson 2020. https://eu.alma.exlibrisgroup.com/view/action/uresolver.do?operation=resolveService&package_service_id=4841648670002418&institutionId=2418&customerId=2415
2
Elementary Algebra Textbook. http://mathrev.redwoods.edu/ElemAlgText/
3
Mathematics Enhancement Programme. http://www.cimt.org.uk/projects/mepres/alevel/alevel.htm
4
Underground Mathematics. https://undergroundmathematics.org/