Thomsen also wrote one of the first systematic treatises on gold bracteates of the Migration period. Thomsen's study of artifacts within the Copenhagen museum were based on associations between stylistic change, decoration and context; he recognised the importance of examining objects from "closed finds", allowing him to determine the associations of common artifacts for various periods (stone - bronze - iron). His results were published in the "Ledetraad til Nordisk Oldkyndighed" (Guideline to Scandinavian Antiquity) in 1836. An English translation was produced in 1848.