While the series was funded by the Australian Government, the authors were free to write on all topics other than technical secrets that were classified at the time, and were not otherwise censored. In line with a request by the US and British governments, the official historians in Australia, Britain, Canada, New Zealand and the US were not given access to Ultra intelligence gained from decrypting German codes. The vetting process for the volumes in the various series also sought to ensure that they did not disclose that German codes had been broken, as this was still classified at the time. Long may have not even been informed that German or Japanese codes had been broken. The authors were given unrestricted access to all other official records, and the Army, Navy and Air series were mainly based on these records and the hundreds of interviews Long had conducted with Australian military personnel during the war. German, Italian and Japanese records were also used to provide information on the enemies the Australian military fought. Draft chapters were sent for comment to the official historians in Britain, New Zealand and the United States.