From the introduction:
"The only reference work for European Formicidae that includes descriptions of most of the species found in Denmark and Fennoscandia is that of Stitz (1939). Redefinitions of certain species, nomenclature changes, the discovery of a few additional species as well as many distribution records have inevitably made the systematic part of that work out of date. The most recent and valuable work dealing substantially with the same fauna is that of Kutter (1977) which, although restricted formally to the species actually recorded within Switzerland, makes descriptive reference to the very few additional species that occur in Fennoscandia. Other standard works that deal with limited fauna in adjacent areas include those of Pisarski (1961, 1975) for Poland, Bolton and Collingwood (1975) for the British Isles and Van Boven (1977) for Belgium. Douwes (1976) following Forsslund (1957b) has brought the Swedish list of Formicidae up to date with a key to the species worker caste. Larsson (1943) dealt with the Danish fauna but this was mainly extracted form the information given by Stitz (1939). The Norwegian fauna was listed and keyed by Holgersen (1944) and the distribution and nomenclature brought up to date by Collingwood (1974).
There exists no standard work to the Finnish fauna. The present work owes much to the revisionary studies of certain genera and species groups including Yarrow (1954, 1955a) for British species allied to Formica fusca and F. rufa respectively, Wilson (1955) for members of the genus Lasius and extended faunal reviews such as that of Dlussky (1967) for the genus Formica in the USSR. Literature references are biased towards papers by Danish and Fennoscandian authors since they deal appropriately with the ecology and distribution of species occurring within the area covered by the president work."