The Wikipedia article on Green Eggs and Ham states that the children's book was banned in China in 1965 for its "portrayal of early Marxism", and that the ban was lifted in 1991. The citations for this are a clickbait article and a New York Public Library blog post.
Is there documentary evidence that this ban actually existed? If so, what was the rationale? I don't understand what the book has to do with early Marxism.