The film is an unofficial sequel to the 1939 Metro-Goldwyn-Mayer film The Wizard of Oz, and is based on L. Frank Baum's early 20th century Oz novels, mainly The Marvelous Land of Oz (1904) and Ozma of Oz (1907).
Head entity: Ozma of Oz
Tail entity: Return to Oz
Relation (head \u2192 tail): based on
Inverse relation (tail \u2192 head): derivative work