Noorifard, M., R. Hamidi Farahani, and E. Hazrati. “The Incidence of Ventilator Associated Pneumonia and Risk Factors in ICU”. Acta Medica Iranica, Vol. 58, no. 9, Nov. 2020, pp. 439-44, https://acta.tums.ac.ir/index.php/acta/article/view/8309.