For Catalpa
Fischer, Theisen, & Lohmann In Kubitzki, K., ed. 2004. The families and genera of vascular plants. VI. Flowering plants – Dicotyledons – Celastrales, Oxalidales, Rosales, Cornales, Ericales. Springer, Berlin. 489 pp.
Gentry, A.H. 1992. Bignoniaceae: Part II (Tribe Tecomeae). Flora Neotropica 25(2): 1-370.
Li, J. 2008. Phylogeny of Catalpa (Bignoniaceae) inferred from sequences of chloroplast ndhF and nuclear ribosimal DNA. J. Syst. Evol. 46: 341-348.
Manning, S.D. 2000. The genera of Bignoniaceae in the southeastern United States. Harvard Papers in Botany 5: 1-77.
Olsen, R.T., and J.H. Kirkbride, Jr. 2017. Taxonomic revision of the genus Catalpa (Bignoniaceae). Brittonia 69: 387-421.
Paclt, J. 1952. Synopsis of the genus Catalpa (Bignoniaceae) III. Candollea 13: 241-285.