Complex sentence: Buchanan discovered documents related to Prescott Bush's business dealings with Nazi industrialist Fritz Thyssen and, together with Stacy Michael, wrote an article about it for the "New Hampshire Gazette".
Split into simpler sentences: Buchanan discovered documents related to Prescott Bush's business dealings with Nazi industrialist Fritz Thyssen. He has also co-written (with Stacy Michael) articles on the matter for the "New Hampshire Gazette".