Fischer, Henry George (1968), Dendera in the Third Millennium B.C. down to the Theban Domination of Upper Egypt., p. 156 & pl. XVII.a
Fischer, H.G. (2002), Titles and epithets of the Egyptian Old Kingdom. Bibliotheca Orientalis 59 (1-2), 18-36, p. 29, no. 1846
Bogdanov, I. & Nikolaev A.H. (2021), Египетский остракон ДВ-1124 эпохи Древнего царства, Reports of the State Hermitage Museum LXXIX, p. 7-11, Comprehensive discussion on the Old Kingdom occurrences of the sign and the corresponding cursive grapheme.