1. Aldridge AE (1975) Taxonomic and anatomical studies in Sonchus L. subg. Dendrosonchus Webb ex Schultz Bip. and related genera. PhD Thesis, University of Reading, Reading
2. Aldridge AE (1976) Macaronesian Sonchus subgenus Dendrosonchus s. l. (Compositae-Lactuceae), including a reappraisal of the species concept and new combinations. Bot Macaronesica 2:81–93
3. Aldridge AE (1979) Evolution within a single genus: Sonchus in Macaronesia. In: Bramwell D (ed) Plants and island. Academic Press, London, pp 249–285
4. Batista F, Bañares A, Caujapé-Castells J et al. (2001) Allozyme diversity in three endemic species of Cistus (Cistaceae) from the Canary Islands: intraspecific and interspecific comparisons and implications for genetic conservation. Am J Bot 88:1582–1592
5. Beardmore JA (1983) Extinction, survival, and genetic variation. In: Schoenwald-Cox CM, Chambers SM, MacBryde B, Thomas L (eds) Genetics and conservation. Benjamin-Cummings, Menlo Park, CA, pp 125–151