Smith, Andrew (1840). Illustrations of the Zoology of South Africa. Smith, Elder, London. The book was published in parts. The part including Plate 48 was published in March 1840. See: Barnard, K.H. (1950). The dates of issue of the "Illustrations of the Zoology of South Africa" and the "Marine Investigations in South Africa". Journal of the Society for the Bibliography of Natural History2 (6): 187–189.
doi.org
Zhao, M. (2023). A near-complete and time-calibrated phylogeny of the Old World flycatchers, robins and chats (Aves, Muscicapidae). Molecular Phylogenetics and Evolution178: 107646. DOI: 10.1016/j.ympev.2022.107646.
worldbirdnames.org
(en) Gill, F, D Donsker, and P Rasmussen (Eds). 2023. IOC World Bird List (v 13.2). Doi 10.14344/IOC.ML.13.2. [1]