Kuptanond, W., S. Chuaykoon, and P. Kamphoosaen. “Low-dose methotrexate and the risk of pneumonia in patients with rheumatoid arthritis”. The Clinical Academia, vol. 41, no. 6, Dec. 2017, pp. 185-92, https://he02.tci-thaijo.org/index.php/theclinicalacademia/article/view/174828.