U. Maesyaroh, L. Munawaroh, H. Sumarti, and R. Adrial, “Analysis of chest X-Ray (CXR) images in COVID-19 patients based on age using the Otsu thresholding segmentation method”, J. Nat. Scien. & Math. Res., vol. 7, no. 2, pp. 59–65, Dec. 2021.