Shahoodh, Mohammed Khalid. “(θ1,θ2) - Derivation Pair on Rings”. Ibn AL-Haitham Journal For Pure and Applied Sciences 35, no. 2 (April 20, 2022): 108–116. Accessed June 28, 2022. https://jih.uobaghdad.edu.iq/index.php/j/article/view/2723.