Halsay, E. Gaudenzio Ferrari. London, 1904, p. 131 [as one of "Four Putti", simply described as "small panels in chiaroscuro"; Eugen Schweizer Collection, Berlin].
Berenson, B. North Italian Painters of the Renaissance. New York, 1907, p. 229 [as late work, but lists 6 putti; Eugen Schweizer Collection, Berlin].
Brizio, A.M. "Studi su Gaudenzio Ferrari," L'Arte, vol. 29 (1926): pp. 158-178, esp. p. 178 [one of 4 panels, in chiaroscuro; erroneously cited as still in Eugen Schweizer Collection, Berlin].
Paintings in the DIA: a checklist of the paintings acquired before June 1965. Detroit, 1965, p. 40.
Berenson, B. Italian pictures of the Renaissance: a list of the principal artists and their works with an index of places. Central Italian and North Italian schools, vol. 1. London, 1968, p. 159.
Mallé, L. Incontri con Gaudenzio. Turin, 1969, p. 249, pl. 247 [dated ca. 1525-27, or a little after].
Fredericksen, B. and F. Zeri. Census of Pre-Nineteenth Century Italian Paintings in North American Public Collections. Cambridge, 1972, p. 70.
Riley, M.W. The History of the Viola. Ann Arbor, 1980, p. 4, (repr.).