1. Hybrid origin of the Oxford Ragwort, Senecio squalidus L : morphological and allozyme differences between S. squalidus and S. rupestris Waldst. and Kit;Abbott;Watsonia,2002
2. The Mediterranean species of Senecio sections Senecio and Delphinifolius;Alexander;Notes R. Bot. Gard. Edinb,1979
3. Anderson E. 1949. Introgressive hybridisation. New York: John Wiley & Sons, Inc.
4. Pollen dispersal and interspecific gene flow in louisiana irises