1. Baas P, E Wheeler, and M Chase. 2000. Dicotyledonous wood anatomy and the APG system of angiosperm classification. Bot. J. Linn. Soc. 134: 3–17.
2. Baas P, S Jansen, E Smets, and EA Wheeler. 2003. Ecological adaptations and deep phylogenetic splits — evidence and questions from the secondary xylem. In: TF Stuessy, V Mayer, and E Hörandl, eds. Deep morphology: toward a renaissance of morphology in plant systematics, pp. 221–240. A.R.G. Gantner Verlag, Liechtenstein.
3. Bate-Smith EC. 1962. The phenolic constituents of plants and their taxonomic significance: I. Dicotyledons. Bot. J. Linn. Soc. 58: 95–173.
4. Behnke H-D. 1991. Distribution and evolution of forms and types of sieve-element plastids in the dicotyledons. Aliso 13: 167–182.
5. Boros CA and FR Stermitz. 1990. Iridoids. An updated review, I. J. Nat. Prod. 53: 1055–1147.