Sowa, Soldan & Braasch 1988. Rhithrogena thracica sp. n. - a new species of mayfly from Bulgaria with a description of subimago and larva of Rh. bulgarica Braasch et al. (1985) (Ephemeroptera, Heptageniidae). Acta Zoologica Bulgarica, No. 36 1988: 31-38