C. Tetikkurt, I. Ozdemir, S. Tetikkurt, N. Yılmaz, T. Ertan, and N. Bayar, “Anxiety and depression in COPD patients and correlation with sputum and BAL cytology”, Multidiscip Respir Med, vol. 6, no. 1, Oct. 2019, doi: 10.4081/mrm.2011.444.