Complex sentence: Reed concentrated on his teaching until 2004, when he started working with Byron Preiss, who contracted to reprint all of the issues of "Baker Street" in a single collection to be distributed by Simon & Schuster.
Split into simpler sentences: Reed concentrated on his teaching until he started working with Byron Preiss in 2004. Preiss had contracted to reprint all of the issues of "Baker Street" into a single collection to be distributed by Simon & Schuster.