“The Effects of Allopurinol on Glutathione Sulfhydryl (GSH) Serum Level, Six Minute Walking Test, and CAT Score of COPD Patients”. Jurnal Respirologi Indonesia 39, no. 3 (July 1, 2019): 169–179. Accessed July 17, 2025. http://www.jurnalrespirologi.org/index.php/jri/article/view/63.