The invertebrates of living and decaying timber in Britain and Ireland by English Nature includes a long section on Diptera. It is in pdf-format and has 467 pages: http://www.englis...nrr467.pdf.
Does someone has a scan of Nartshuk E.P. 2003. Key to families of Diptera (Insecta) of the fauna of Russian and adjacent countries. Proceedings of the Zoological Institute Vol. 294: 1-252 for me?