^Florian Hardwig. Lieder zur Weihnachtszeit (1940). Fonts in Use. 2015-12-26. (原始内容存档于2021-05-06) (英语). It used to be common to mark omitted double letters with an overbar, especially for 'mm' and 'nn'. These abbreviations come in handy when lyrics have to match the musical notes, see 'da kom[m]t er her'.