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

MathSciNet gives this paper:

MR0552072
Blakley, Bob; Blakley, G. R.
Security of number-theoretic public key cryptosystems against random attack. I.
Cryptologia 2 (1978), no. 4, 306–321.

and also this one, which was received on April 6, 1978:

MR0557125
Smith, Donald R.; Palmer, James T.
Universal fixed messages and the Rivest-Shamir-Adleman cryptosystem.
Mathematika 26 (1979), no. 1, 44–52.

These papers are dated before the paper by Rivest mentioned in the comments, which was received on April 4, 1979:

MR0537789
Rivest, Ronald L.
Critical remarks on: "Critical remarks on some public-key crypto systems" by T. Herlestam.
BIT 19 (1979), no. 2, 274–275.