A search of U.S. copyright renewal records reveals that while copyright on the text of the book was renewed by Alberta Thompson, Lion Books (or assignee) renewed no copyright to the other content of the published volume.
A search of copyright renewal records reveals no evidence that the unidentified creator of the painting that constitutes the primary original substance of the cover renewed copyright on the artwork, if any.
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 (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.