Husk, William Henry. Songs of the Nativity Being Christmas Carols, Ancient and Modern. London: John Camden Hotten, 1868 reprinted by Norwood Editions, Norwood, PA, 1973. Digitally reproduced and annotated by A Treasury of Christmas Carols: The Hymns and Carols of Christmas
jstor.org
Spears, James E. Folklore, Vol. 85, No. 3. (Autumn, 1974), pp. 194-198. JSTOR