^John Shiffman, Robert K. WittmanPriceless : How I Went Undercover to Rescue the World's Stolen Treasures by Robert K. Wittman and John Shiffman (2011, Paperback)ISBN 9780307461483 (revised Feb 2017)
^WITTMAN, ROBERT K.SHIFFMAN, JOHN (2015). Priceless : How I Went Undercover to Rescue the World's Stolen Treasures, Broadway Books. BiggerBooks. ISBN 9780307461483 (revised Jan 2024)
^ (2013). Priceless : How I Went Undercover to Rescue the World's Stolen TreasuresECampus. ISBN 9780307461483 (revised Jul 2016)