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Summary
DescriptionSinbadthesailor01.jpg
English: Film poster for the animated cartoon Sinbad the Sailor from 1935.
What's at the lower right is the name of the litho company who printed the poster--I can't make it all out but can see "Litho Co." when zoomed/enlarged. There are no other visible marks.
To be sure the poster is in the public domain, a search was done for original registrations in both motion pictures and artwork for the year 1935; nothing pertaining to Iwerks, Powers, or Celebrity Productions was discovered. An artwork by John S. Rork, "Mr. Kizmet, Sinbad and the Princess", was registered in 1936. There are no listings for "Sinbad" in either section for 1935. There's no evidence that this material was ever under copyright.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (50 p.m.a.), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.