The accuracy of various allegations made in the book by Wright was questioned in a review of "Spycatcher" published by the Center for the Study of Intelligence, an in-house think tank for the CIA. While admitting (on page 42) that the book included "factual data", the document stated that it was also "filled with errors, exaggerations, bogus ideas, and self-inflation". The review added (on page 45) that "Gen. Oleg Kalugin, former Chief of Counterintelligence" had confirmed to the author that Hollis had not worked for the KGB.