سهام يوسف علي و عبد الله إبراهيم نور الدين 2018. 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 . 17, 3 (Dec. 2018). DOI:https://doi.org/10.51984/jopas.v17i3.281.