1. Andersen, S., 1970. The relative pollen productivity and pollen representation of north European trees, and correction factors for tree pollen spectra. Dan. Geol. Unders. II, Række 96, 1–96.
2. Andersen, S.T., 1973. The differential pollen productivity of trees and its significance for the interpretation of a pollen diagram from a forested region. In: Birks, H.J.B., West, R.G. (Eds.), Quaternary Plant Ecology. Blackwell, Oxford, pp. 109–16.
3. Behre, K.-E., 1986. Anthropogenic Indicators in Pollen Diagrams. A.A. Balkema, Rotterdam.
4. Bennett, K.D., 1998. http://www.kv.geo.uu.se/pc-dicto-notes.html-note24, as updated 26/11/1998.
5. Recent plant nomenclatural changes and pollen morphology in the British Isles;Bennett;Quat. Newsl.,1994