C. Tet Vui, L. Chiew Han, C. Suan Cheng, S. Kambe, and R. Abd Shukor, “Hole Concentration in GdBaSrCu3-xZnxO7-δ System: Interplay among Superconductivity, Stripe Order and Pseudogap”, INTI Journal, vol. 2019, Feb. 2020.