Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.
Q: Passage: However, his religious views remain uncertain due to other statements that he made. For example, in his article, 'A Machine to End War', published in 1937, Tesla stated: Question: What article was published in 1937?
A: 
"A Machine to End War"