ChoK.C., BakerS.R.Extraluminal air. Diagnosis and significance. Radiol Clin North Am.1994; 32(5): 829–44.
2.
ChiuY.H., ChenJ.D., TiuC.M., ChouY.H., YenD.H., HuangC.I.Reappraisal of radiographic signs of pneumoperitoneum at emergency department. Am J Emerg Med.2009; 27(3): 320–7.