Tet Vui, Chong, et al. “Hole Concentration in GdBaSrCu3-XZnxO7-δ System: Interplay Among Superconductivity, Stripe Order and Pseudogap”. INTI Journal, vol. 2019, Feb. 2020, https://iuojs.intimal.edu.my/index.php/intijournal/article/view/394.