file 1: 1906-1909 with material assumed to be those dates.
file 2: January - 8 October 1910.
file 3: 12 October 1910 - December 1910, with material assumed to be 1910.
file 4: January - June 1911.
file 5: July - December 1911, with material assumed to be 1911.
file 6: 1912, with material assumed to be 1912.