2007, Alan H. Freeman, Radiology of the Stomach and Duodenum, Preoperatively and intraoperatively it is difficult to distinguish benign and malignant lesions; all may demonstrate a mixture of intramural, endogastric and exogastric appearances.
1957, Rousseau Hayner Flower, ‎Curt Teichert, The cephalopod order Discosorida, Vexing are two exogastric genera of the Simard limestone.
1998, Norman Dennis Newell, Bivalves: An Eon of Evolution, I interpret Mellopegma as exogastric and separate it from Peel's (1991) class Helcionelloida because of its extremely narrow aperture with uniformly ventrally curved lateral margins.
