Complex sentence: Early sources on Richard Neville fall into two categories, one being the sympathetic chronicles of the early Yorkist years, or works based on these, such as the "Mirror for Magistrates" (1559).
Split into simpler sentences: Early sources on Richard Neville fall into two categories. The first are the sympathetic chronicles of the early Yorkist years, or works based on these, such as the "Mirror for Magistrates" (1559).