P. E. K. K. A.  VILKAMAA and Hippa, H., ?Review of the Nearctic Claustropyga Hippa, Vilkamaa & Mohrig (Diptera, Sciaridae) with the description of three new species?, Zootaxa, vol. 1552, pp. 53?68, 2007.

H.  Hippa and VILKAMAA, P. E. K. K. A., ?New species and records of Keilbachia Mohrig (Diptera, Sciaridae) from the Oriental region?, Zootaxa, vol. 1622, pp. 57?68, 2007.

P. E. K. K. A.  VILKAMAA, Salmela, J., and Hippa, H., ?Black fungus-gnats in deciduous forest habitat in northern Europe, with the description of Bradysia arcula sp. n. (Diptera: Sciaridae)?,  Entomologica Fennica, vol. 18, 2007.