1. L. A. Alice and C. S. Campbell, Am. J. Bot., 86, 81 (1999).
2. USDA-ARS-GRIN database, 2003. USDA, ARS, National Germplasm Resources Laboratory, Beltsville, MD. Available on-line at: http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?32443.
3. Y. Heslop-Harrison, Flora Europaea, Ed. T. G. Tutin, University Press, Cambridge 1968, pp. 7–10.
4. Wl. Szafer, St. Kulczynski, and B. Pawlowski, Rosliny polskie, 1, PWN, Warszawa 1986, pp. 287–288.
5. E. N. Novruzov, Rast. Resur., 24, 48 (1988).