It is a translation of a comparatively old-fashioned book by Yu. Korshunov and P. Gorbunov. Both authors changed their minds later, it reflected in the following publications by Korshunov and a new book by P. Gorbunov (the main tendency is towards merging taxa by Gorbunov and dividing them by Korshunov).
The translation of their common work while their opinions mostly coincided see here.
P. Gorbunov has published a new book:
P. Gorbunov. 2001. Butterflies of Russia: classification,
keys for identification, genitalia. - Thesis, 2001, Ekaterinburg - 320 p.
The text contains diagnostic keys for the families, genera
and species, verbal description of their genitalia, small distribution maps,
diagnostic characters of subspecies accepted as valid, complete synonymy for all
the taxa assumed as valid restricted to those synonyms described from the
Russian territory (but with main species synonyms), and English
translations of original descriptions of taxa considered as valid if they were in Russian. The genitalia of almost all species are illustrated, there are colour plates with 119 photos of butteflies in Nature representing genera, but no plates with
spread specimens. Hard cover, 1.1 kg. The author is rather a lumper and accepts only 472 species and not so many subspecies inside them. He has a clear Mayerian methodology, consequently applied throughout, of what to consider different species and different subspecies. All the taxonomical decisions are argumented, that is a good basis for either acceptance or criticism.
PURCHASE: mail to P. Yu. Gorbunov, email@example.com other to O. E. Kosterin, firstname.lastname@example.org