M. T. Nikolova, S. Berkov, M. Dimitrova, B. Sidjimova, S. Stoyanov, and M. Stanilova, “Phenolic acid profiles of endemic species Verbascum anisophyllum and Verbascum davidoffii: Phenolic acid profiles of Verbascum species”, J. BioSci. Biotechnol., vol. 6, no. 3, pp. 163–167, Mar. 2018.