Norris, D. Ryan, Marra, Peter P., Kyser, T. Kurt, Ratcliffe, Laurene M., and Montgomerie, Robert. 2007. "
Continent-wide variation in feather colour of a migratory songbird in relation to body condition and moulting locality."
Biology Letters, 3, (1) 16–19.
https://doi.org/10.1098/rsbl.2006.0572.