D. Ucel Cayhan, M. Akif Ustuner, and I. Parlak, “Comparision of ultrasonography with direct radiography and aspiration for the confirmation of nasogastric tube placement among intubated patients in the emergency servise: A prospective,single-blind,cross-sectional study ”, annalsmedres, vol. 28, no. 3, pp. 0542–0546, May 2021.