29th April, 1965.
Dear Marshall and Jim,
I am writing to you both because you are the two Chairman of the Informal Exchange Group on Nucleic Acids and the Genetic Code.  I want to suggest that at the end of the Gordon Conference on Nucleic Acids a statement be issued on the state of that Genetic Code.  As you know I have found myself involved in this, but as a collater of information rather than a producer.  I am constantly having to provide copies of my private version of the code to interested people.  Moreover this has been of some use.  For example it has helped Streisinger et al. decipher their (- +) double mutant in the phage lysozyme.  Also, as a result of it, one abnormal haemoglobin has already been shown to be incorrect by a colleague of Lehmann's (Hb I should be Lys Glu, not Lys Asp).
This year's Gordon Conference should provide an ideal opportunity, not to present a final version of the code, but the best version of most of it.  It will also be of value since it will show what remains to be established.
The exact mechanism of publication we could leave till the Conference.  Probably a short, joint, note to Science would be the best.  However, I thought it might be sensible to sound you both out on the matter now.  Its obvious that no one person has enough certain data to establish the code by himself, and also that by pooling all the information we can already arrive at most of the code.
I am sending a copy of this to Gobind Khorana.
Hoping to hear from both of you,
F. H. C. Crick