No copyright notice is shown on the front side. The back side is unavailable. The seller stated in the eBay page above that "[i]f the photograph contains relevant information such as a stamp or news article, marks, stains or anything written in it, the back will be revealed. If not, only the front of the photo is shown and the back can be assumed plain and clear." Thus it can be assumed that the back side does not have a copyright notice. Furthermore, the uploader contacted the seller. The seller confirmed that there are no copyright notices on the front or back side.
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.
Uploaded a work by Most likely Monogram Pictures (the production company of ''Shadows over Chinatown'') from [https://www.ebay.com/itm/162609836602 eBay] <sub>([https://web.archive.org/web/20210828180142/https://www.ebay.com/itm/162609836602 archived])</sub> with UploadWizard