1. Agababyan, V.S. 1961. A contribution to the palynomorphology of the family Hydrangeaceae Dum. Izv. Akad. Nauk SSSR, Ser. Biol. 14 (11): 17–26.
2. Albach, D.C. et al. 2001. See general references.
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4. APG (Angiosperm Phylogeny Group) 1998. See general references.
5. Axelrod, D.I. 1987. The late Oligocene Creede flora, Colorado. Univ. Calif. Publ. Geol. Sci. 130: 1–235.