Brockhaus-1837: Hardenberg [2] · Hardenberg [1]
Brockhaus-1911: Hardenberg [3] · Hardenberg [2] · Hardenberg
Eisler-1912: Hardenberg, Friedrich von
Herder-1854: Hardenberg [3] · Hardenberg [2] · Hardenberg [1]
Meyers-1905: Hardenberg [2] · Hardenberg [1]
Pataky-1898: Hardenberg, Sophie v. · Hardenberg, Magda · Hardenberg, Henriette Luise Juliane
Pierer-1857: Hardenberg-Reventlow · Neu-Hardenberg · Hardenberg [3] · Hardenberg [1] · Hardenberg [2]