Borghouts, J. F. (2010), Egyptian: an introduction to the writing and language of the Middle Kingdom, 2 vols. Egyptologische Uitgaven 24, page 123, note 2
                   
                   
                
                        
                    
                        Gardiner, Alan Henderson (1957), Egyptian grammar being an introduction to the study of hieroglyphs, 3rd, revised edition, page 505