World 4-1 (Super Mario Bros.) - Super Mario Wiki, the Mario encyclopedia

World 4-1 is the first level of World 4 in Super Mario Bros. and the thirteenth level overall in said game. This level introduces the Lakitu and Spiny enemies in the series.

Super Mario Bros. - Wikipedia

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Super Mario Bros. 4 Level I: World 1-4 by stephen718 on DeviantArt

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