Ali, Siham, and Abdallah Nuraldeen. “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, pp. 10-17, https://doi.org/10.51984/jopas.v17i3.281.