1. Chrtek J. 1995. Notes on Hieracium alpinum and Hieracium nigrescens groups (section Alpina Fries) in the Eastern Sudeten (Mt. Králický SněŽník, the Hrubý Jeseník Mts.). Preslia 67: 97–106.
2. Chrtek J. 1997. Hieracium decipientiforme (the H. nigrescens group) — an interesting species of the Ukrainian Carpathians. Preslia 69: 121–128.
3. Chrtek J. 2004. Hieracium L., pp. 540–701. In: Slavík B., Štěpánková J. & Štěpánek J. (eds), Květena České Republiky vol. 7. Academia, Praha.
4. Chrtek J. & Mráz P. 2007. Taxonomic revision of Hieracium nigrescens agg. in the Western Carpathians. Preslia 79: 45–62.
5. Coldea G. 1991. Prodrome des associations végétales des Carpates du Sud-Est (Carpates Roumaines). Documents Phytosociologiques Nouv. Sér. 13: 315–539.