Many of the letters currently held in the collection are copies from originals, but as the records have been so well-kept in the 20th century, their authenticity is not in question. The time period of the correspondence is 1922 to 1945.
Several letters within the archive are reproductions of original documents; however, due to meticulous record-keeping in the 20th century, their genuineness is unquestionable. The timeframe for these communications ranges from 1922 to 1945.