Reference
Kirill A. Kolesnichenko (1999): A review of the East-Palaearctic taxa of the Melitaea didyma (Esper, 1779) group - 1. The M. ala (Staudinger, 1881) -M. chitralensis (Moore, 1901) -complex (Lepidoptera, Nymphalidae) – Atalanta – 30: 87 - 117.