November 16, 1962
Dear Francis:
Congratulations!  You must have received many such exclamations, but I just want to say that I was tremendously glad you had been awarded this distinction.  Your Nobel award is richly deserved and long overdue.  Again, congratulations.
I am enclosing a manuscript which has just gone off to PNAS. Quantitative work now in progress clearly shows that some codewords are triplets.  I will send you the data when they are complete.
With all best wishes, I remain,
Sincerely yours,
Marshall W. Nirenberg