^Peter F. Stevens and Hilary M. Davis. 2005. The Angiosperm Phylogeny Website - a tool for reference and teaching in a time of change. In: Proceedings of the American Society for Information Science and Technology, vol. 42, issue 1. (on-line pdf document, cached May 24, 2013.)
Note: This is a selected list of the more influential systems. There are many other systems, for instance a review of earlier systems, published by Lindley in his 1853 edition, and Dahlgren (1982). Examples include the works of Scopoli, Batsch and Grisebach.