Source & provenance
Hardi Döhler — reference attribution
Independent historical research on US regular Zippo case and insert construction, provided directly by the author; summarized with permission to use data. Not an official Zippo Manufacturing Company publication. No third-party bottom-stamp illustrations reproduced.
Original source / further reading
Credit and copyright for individual images are shown on their corresponding reference pages. Attribution does not grant a reuse license.
Historical construction research
Independent collector research supplied directly by Hardi Döhler, author of Click Ratz-Fump. This is not an official Zippo Manufacturing Company publication. Ranges primarily cover US regular production; special lines and repairs can differ. No original chart or third-party bottom-stamp artwork is reproduced.