found:Work cat.: Unverhau, D. Das Danewerk 1842, 1988.
found:LC data base, 10/25/91.
found:PREM, 10/25/91.
found:Old catalog heading(Danewerk, X Dannewerk, X Dannevirke, X Danevirke)
found:Britannica Micro.(Danevirke, also spelled Danewerk, Danewirk: medieval fortification in Denmark. Regarded as the most extensive historic monument in Scandinavia, Danevirke was a system of earthworks, built over a period of 350 years, to protect Denmark from invaders from the south.)
found:Times atlas(Dannewerk: area now part of Schleswig-Holstein, Germany)