NBC via the Bureau of Industrial Service. It was common at the time for networks, show sponsors and studios to use an ad or publicity agency to distribute publicity material. The "bureau" was used widely by those in the industry and was a division of ad agency Young & Rubicam.
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.