Complex sentence: In 1995 he started working exclusively for Terry Pratchett's Discworld series, and his Discworld art, and many descriptions of the pieces, are included in "The Pratchett Portfolio" (1996) and "The Art of Discworld" (2004).
Split into simpler sentences: In 1995 he started working exclusively for Terry Pratchett's Discworld series. His Discworld art, and many descriptions of the pieces, are included in "The Pratchett Portfolio" (1996) and "The Art of Discworld" (2004).