Complex sentence: The authenticity of Cowell's "Reflections", accepted by Shakespearean scholars for many years, was challenged in 2002-2003 by John Rollett, Daniel Wright and Alan H. Nelson.
Split into simpler sentences: The authenticity of Cowell's "Reflections" was accepted by Shakespearean scholars for many years. However, the authenticity of the manuscript was challenged in 2002-2003 by John Rollett, Daniel Wright and Alan H. Nelson.