Reference

Florian Schiestl, Manfred Ayasse, Hannes F. Paulus, D. Erdmann, Wittko Francke (1997): Variation of the pollinator-attracting odor signals and reproductive success in Ophrys sphegodes subsp. sphegodes Miller (Orchidaceae). – Mitt.dt.Ges.alg.angew.Ent. – 11: 477 - 480.