et. al, A. C. V. “THE INCIDENCE AND RISK FACTORS FOR VENTILATOR ASSOCIATED PNEUMONIA (VAP) IN CRITICAL CARE UNIT”. International Journal of Advanced Science and Technology, Vol. 29, no. 04, Feb. 2020, pp. 1183 -87, http://sersc.org/journals/index.php/IJAST/article/view/4857.