1. 6 (Fensterglas ritzt schwer, Stahlfeile ritzt)

    http://thesauri.dainst.org/_febe3059

  2. 6-10 (durissimo, non scalfibile con lama di coltello)

    http://thesauri.dainst.org/_f434ad9d

  3. 60 As

    http://thesauri.dainst.org/_436ece23

  4. 60 As

    http://thesauri.dainst.org/_72e01c71