Isa, R. B., and D. M. Abeku. “Procurement Systems and Contract Pricing Methodsin the Construction Industry: Perspective of Contractors in Kaduna Metropolis, Nigeria”. International Journal of Creativity and Technical Development (IJCTD), vol. 3, no. 2, July 2019, pp. 1-12, http://icidr.org.ng/index.php/Ijctd/article/view/712.