1. Wagenitz, G. Problems of the Balkan Flora and Vegetation; Bulgarian Academy of Sciences, 1975; pp 223–228.
2. Wagenitz, G.; Hellwig, F. H. Proceedings of the International Compositae Conference, Vol. 1; Hind, D. J. N.; Beentje, H. J., Eds. Royal Botanic Gardens: Kew, UK, 1996; pp 491–510.
3. Heywood, V. H.; Harborne, J. B.; Turner, B. L. In The Biology and Chemistry of the Compositae; Academic Press: London, 1977; pp 999–1015.
4. Genome size in Bulgarian Centaurea s.l. (Asteraceae)
5. Susanna, A. N.; Garcia-Jacas, N. The Tribe Cardueae. In The Families and Genera of Vascular Plants, Vol. VIII; Kadereit, J. W.; Jeffrey, C., Eds. Springer Verlag: Berlin, Heidelberg, 2007; pp 123–146.