- The Skull's chronological first appearance, in Judomaster #92, was actually published after his debut appearance, which takes place much later.
- This version of Smiling Skull, including all history and corresponding appearances, was erased from existence following the collapse of the original Multiverse in the 1985–86 Crisis on Infinite Earths limited series. Even though versions of the character may have since appeared, this information does not apply to those versions.
- 5 Appearances of Rudolf Wolk (Earth-Four)
- 2 Images featuring Rudolf Wolk (Earth-Four)
- Quotations by or about Rudolf Wolk (Earth-Four)
- Character Gallery: Rudolf Wolk (Earth-Four)
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