||Alistair M. Hetherington1 F. Ian Woodward. The role of stomata in sensing and driving environmental change. Nature. 2003 Aug 21 424(6951):901-8. p. 902 right column, bottom paragraphPubMed ID12931178
||Willmer, C. & Fricker, M. Stomata 2nd edn (Chapman & Hall, London, 1996).
||Depending on the species and the environmental conditions stomata range in size from about 10 to 80µm in length and occur at densities between 5 and 1,000mm^2 (BNID 101758) of epidermis (primary source and Fig. 3a). In spite of this wide variability there is a strong and general relationship between density and size (Fig. 3a) for different plant groups (grasses and non-grasses), fossil leaves and for different stomatal distributions on either one or both leaf surfaces.