For Gentianella
Gillett, J.M. 1957. A revision of the North American species of Gentianella Moench. Ann. Mo. Bot. Garden 44: 195-269. Google Scholar
Pringle, J.S. 2023. Gentianaceae. Pp. 3-92 In Flora of North America Editorial Committee. 2023c. Flora of North America north of Mexico. Volume 14, Magnoliophyta: Gentianaceae to Hydroleaceae. Oxford Univ. Press, New York, NY. 505 pp. Google Scholar
Struwe, L., and J.S. Pringle. 2018. Gentianaceae. In Kadereit, J., & V. Bittrich. 2018. The families and genera of flowering plants. XV. Flowering plants. Eudicots. Apiales, Gentianales (except Rubiaceae). Springer, Cham. Google Scholar
Wood, C.E., and R.E. Weaver, Jr. 1982. The genera of Gentianaceae in the southeastern United States. J. Arnold Arb. 63: 441-487. Google Scholar
Yuan, Y.-M., and P. Küpfer. 1995. Molecular phylogenetics of the subtribe Gentianinae (Gentianaceae) inferred from the sequences of internal transcribed spacers (ITS) of nuclear ribosomal DNA. Plant Systematics and Evolution 196: 207-226. Google Scholar