I do believe this is the VERY FIRST time I have ever heard this question raised....................my response?
I have not the slightest idea.............Have you tried to Google the letters to see what you come up with? My suspicion is that they do not now exist.........but that is pure speculation based on the idea that if they did still exist, we would be well aware of them, for they would have been widely publicized as is the Word of God...........
BECAUSE this question is so very unique.........I will try to add to your "rep..........."
God bless