National Air and Space Museum / Smithsonian (detailed catalog entry identifying navigator Max Prüß using a sextant). timeandnavigation.si.edu+1
Airships.net (image featured in their “photo of the day” / Graf Zeppelin image posts). airships.net
Alamy (stock-photo listing / archive). Alamy+1
Getty Images (stock-photo search results include Graf Zeppelin images and related shots). gettyimages.co.uk+1
Picryl (historic-photo aggregation pages). picryl.com
CIA Reading Room (a declassified/archival page referencing photographs taken during Graf Zeppelin flights). cia.gov
Pinterest (user pins that point back to stock/archival pages hosting the image). Pinterest+1
Notes and caveats:
Many more copies may exist (additional blogs, museum mirrors, social-media posts, or other stock sites) — aggregate sites often repost the same original, so the true number of pages showing the picture is higher and changes over time.
The Smithsonian / NASM entry is the clearest archival source for this particular image and provides the authoritative caption and metadata. timeandnavigation.si.edu
Want me to try to produce a longer list (with direct links and thumbnails) of other pages hosting the same image?"
There's clearly value in this service so long as you follow the warnings. DaveP
