Lopes, L.E. & Gonzaga, L.P. (2012)

Clinal pattern of morphological variation in Sakesphorus luctuosus (Lichtenstein, 1823), with comments on the enigmatic Sakesphorus hagmanni Miranda-Ribeiro, 1927 (Passeriformes: Thamnophilidae)

. Zootaxa, 3569 (1), 41–54.