By BPP Learning Media
By John Andrew, III, Graham Roberts, Andrew Moore
By Michael R. Bloomberg, Matthew Winkler
By William O'Neil
By E.C. Oliver, R.J. Chapman, C.S. French
By Kaplan
By Kaplan Publishing
By Aubrey Penning
By Aubrey Penning, Michael Fardon
By Jo Osborne
By David Cox, Michael Fardon
By Edward W. Davis, John Pointon
By The Economist
By John Henderson (Birkbeck, University of London), Alastair Mcguire, Gavin Mooney (Curtin University, Perth, Australia)