Munroe, Mary H. (2004). „Cambridge Information Group Timeline”. The Academic Publishing Industry: A Story of Merger and Acquisition. Архивирано из оригинала 2014-10-20. г. — преко Northern Illinois University.
Munroe, Mary H. (2004). „Cambridge Information Group Timeline”. The Academic Publishing Industry: A Story of Merger and Acquisition. Архивирано из оригинала 2014-10-20. г. — преко Northern Illinois University.