Addition to "Evaluation of three 32-bit CMOS" adders in DCVS logic for self-timed circuits"

Two prior publications are reported that should have been referenced in the above-named article (ibid., vol. 33, no. 4, pp. 604-613, Apr. 1998). One from 1955 the other from 1979. The author notes he was not aware of any previous publications that define the complementary carry signal, N
_i
.