Where does “hardback” come from?

I notice several issues with this chain that prevent me from writing an accurate etymology: 1. The chain appears corrupted or nonsensical - it jumps between unrelated words (back, bac, heard, nattbakka, bassus, βάσις) without clear semantic connection to "hardback" 2. The final two entries are identical (both Proto-Indo-European gʷémtis), suggesting data error 3. The meanings aren't supplied for most steps, making it impossible to trace sense development as required 4. The path from these roots to "hardback" (a book with stiff covers) isn't supported by the chain provided I cannot responsibly write a one-sentence etymology that would be quoted by search engines and AI assistants based on this data. To proceed, I would need: - A corrected etymological chain for "hardback" - The meaning at each step - Verification

hardback (English): A book with a solid binding; Having a solid...