"The volumes are, in short, extremely comprehensive and are as well researched and authenticated as the elusive activities of Communist parties, many of them clandestine, can be. The tone of the essays, meanwhile, is detached and impartial. While individual authors may sometimes lean on rumour and hearsay where concrete evidence is lacking, none of them can be charged with gratuitously perpetrating a distorted impression of world communism or of displaying a bias toward individual parties."