Prefixes for Imperial bank of Canada notes

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I recently acquired a pair of 1939 Imperial bank $10 notes with the serial numbers E053458 & E053459. I was wondering if anyone knew how many different series(?) letters were used by the Imperial bank on these notes. I've seen E, F and H on 1934 and E and H on 1939 $10's  but  I don't recall seeing any others. I figure if anyone knows, it would be Bob the Omnipotent .

Thanks
Rob

He isn't omnipotent, but he does know of these prefix series for Imperial Bank $10's:
1934:  plain, E, F, G, H, J
1939:  plain, E
There is also a "G" reference in an auction catalogue for the 1939 $10 but it is probably an error and a $5 was intended.
Don Allen worked out the math behind these prefixes and the varying logos, and published his findings in his Canadian Coin News column.  I'm sorry I can't put my hands on it immediately to give you the date and page.