ŠUMBEROVÁ, Kateřina, Rossen TZONEV and Vladimir VLADIMIROV. Bidens frondosa (Asteraceae) - a new allien species for the Bulgarian flora. Phytologia Balcanica. Sofia: Bulgarian Academy of Sciences, 2004, vol. 10, 2-3, p. 179-181. ISSN 1310-7771.
TZONEV, Rossen and Kateřina ŠUMBEROVÁ. New data on the chorology of some little known adventive species on the banks of the Danube River in Bulgaria. Phytologia Balcanica. Sofia: Bulgarian Academy of Sciences, 2004, vol. 10, 2-3, p. 207-209. ISSN 1310-7771.