When was the first appearance of the abbreviation RSA?

Question

When was the first publication of the abbreviation RSA (Rivest, Sharmir, Adleman) because it does not appear in Martin Gardner’s article of 1977 which is at the following url: https://simson.net/ref/1977/Gardner_RSA.pdf

Answer 1

Nor does it appear in A method for obtaining digital signatures and public-key cryptosystems (Communications of the ACM Volume 21 Issue 2, Feb. 1978 Pages 120-126), which was Rivest-Shamir-Adleman's original publication. It is hard to pinpoint the watershed with such obvious abbreviations, but MathSciNet shows Blakley-Blakley Security of number-theoretic public key cryptosystems against random attack I (Cryptologia 2 (1978), no. 4, 306–321) as the earliest occurrence. The trio founding RSA Data Security, Inc. in 1982 (now RSA Security LLC) probably solidified the usage.