سهام يوسف علي و عبد الله إبراهيم نور الدين. “An Estimation of Import Demand Function for Wheat in Libya(1980-2016) Empirical Study Using Simultaneous Integration With Thresholds (Co-Integration With Regime Shift )”. Journal of Pure & Applied Sciences, vol. 17, no. 3, Dec. 2018, doi:10.51984/jopas.v17i3.281.