Bibliography
Gardiner, Alan Henderson (1957), Egyptian grammar being an introduction to the study of hieroglyphs, 3rd, revised edition, page 481
Schenkel, Wolfgang (1991), Tübinger Einführung in die klassisch-ägyptische Sprache und Schrift. Tübingen, page 29, rather glottal stop;
https://doi.org/10.11588/diglit.13942#0031