Complex sentence: In 1995, he and Tom Bowman co-wrote a six-part explanatory series of articles on the National Security Agency, the first major investigation of NSA since James Bamford's 1982 book The Puzzle Palace.
Split into simpler sentences: In 1995, he and Tom Bowman wrote series of articles, six in all, on the National Security Agency. This was the first major investigation of the NSA since James Bamford's 1982 book The Puzzle Palace.