Graves, G. R., Lane, D. F., O’neill, J. P., & Valqui, T. (2011). A distinctive new subspecies of the Royal Sunangel (Aves: Trochiliformes; Heliangelus regalis) from the Cordillera Azul, northern Peru. Zootaxa, 3002(1), 52–58. https://doi.org/10.11646/zootaxa.3002.1.5