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This unification , which was observed by Michael Faraday , extended by James Clerk Maxwell , and partially reformulated by Oliver Heaviside and Heinrich Hertz , is one of the key accomplishments of 19th - century mathematical physics .
 Michael Faraday, James Clerk Maxwell, Oliver Heaviside, Heinrich Hertz
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Answer:
 Michael Faraday, James Clerk Maxwell, Oliver Heaviside, Heinrich Hertz