There are no copyright markings as can be seen at the full view link. A&M did not mark this special ad section with copyright mark(s); the Billboard copyright covers editorial content only-not advertisements, which would need to have their own copyrights for protection. These pages are marked "Special Section sponsored by The Carpenters" at page bottoms. see page 14 Special section for mark.
The ad is not covered by any copyrights for Billboard.
"A notice for the collective work will not serve as the notice for advertisements inserted on behalf of persons other than the copyright owner of the collective work. These advertisements should each bear a separate notice in the name of the copyright owner of the advertisement."
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.