J. Stojkovikj, B. Zafirova-Ivanovska, B. Kaeva, S. Anastasova, I. Angelovska, and D. Stojkovikj, “The Prevalence of Diabetes Mellitus in COPD Patients with Severe and Very Severe Stage of the Disease”, Open Access Maced J Med Sci, vol. 4, no. 2, pp. 253–258, May 2016.