Martins, Ludwig; Hellwig, Frank H. (agosto de 2005). «Systematic position of the genera Serratula and Klasea within Centaureinae (Cardueae, Asteraceae) inferred from ETS and ITS sequence data and new combinations in Klasea». Taxon54 (3): 632-638. JSTOR25065420. doi:10.2307/25065420.
Martins, Ludwig; Hellwig, Frank H. (agosto de 2005). «Systematic position of the genera Serratula and Klasea within Centaureinae (Cardueae, Asteraceae) inferred from ETS and ITS sequence data and new combinations in Klasea». Taxon54 (3): 632-638. JSTOR25065420. doi:10.2307/25065420.