Complex sentence: The first two novels were written by, but they were slow paced, so another author was brought in with later stories being published under the house name, Grant Stockbridge; most of the Spider novels were written by Norvell Page.
Split into simpler sentences: The first two novels were written by, but they were slow paced, so another author was brought in. Later stories were published under the house name, Grant Stockbridge; most of the Spider novels were written by Norvell Page.