Keys to the insects of the European part of the USSR. Vol. 3. Hymenoptera. Part 6. By Zhelokhovtsev A.N., Tobias V.I., Kozlov M.A.
Keys to the Fauna of the USSR 158: 1-432, 1993
English translation from the 1988 Russian edition [which i use].
Covers the 'Symphyta' (close to 900 spp.) and a number of minor taxa of parasitic wasps (Trigonaloidea, Stephanoidea, Evanioidea, and Paxylommatidae). Somewhat outdated yet thorough treatment with lots of useful info.