“IR and Uv-Visible Study of the Thermal Stabilization for Pvc Stabilized With ( Ho,Tb and Dy ) Stearate and Synergistic Mixtures”. Ibn AL-Haitham Journal For Pure and Applied Sciences, vol. 19, no. 4, Dec. 2017, pp. 90-98 E, https://jih.uobaghdad.edu.iq/index.php/j/article/view/1675.