Jennifer Marsh, John Gray and Antonella Tosti, Healthy Hair (Springer, 2015), p. 117. DOI (for the relevant chapter): DOI: 10.1007/978-3-319-18386-2_7.
Zoe Diana Draelos, "Hair Cosmetics", in Hair Growth and Disorders, ed. by Ulrike Blume-Peytavi, Antonella Tosti and Ralph M. Trüeb (Springer, 2008), pp. 499–513 (p. 500) DOI: 10.1007/978-3-540-46911-7_25.