<ref name="Seifert_1992">{{cite journal |first1=B. |last1=Seifert |year=1992 |title=''Formica'' ''nigricans'' Emery, 1909 - an ecomorph of ''Formica'' ''pratensis'' Retzius, 1783 (Hymenoptera, Formicidae) |url=https://antcat.org/documents/2702/2560.pdf |journal=Entomologica Fennica |publisher= |volume=2 |issue= |pages=217–226 |doi= }}</ref>