Nazarov, M.; Velev, N.; Mardari, C.; Grigorov, B.; Georgiev, S.; Genova, B.; Vassilev, K. Syntaxonomy and Ecology of Petasites Albus, P. Hybridus and P. Kablikianus Phytocoenoses in Bulgaria and Romania. C. R. Acad. Bulg. Sci. 2022, 75, 43-55.