The one which begins with "I am in receipt of a memo from some character using the pseudonym D.C. Fontana" (and then subsequently refering to the name D.C. Fontanta in quotation marks all the way through the rest of the memo) is one that always raises a chuckle from me.
There aren't any quotation marks around Fontana's name in that memo (see The Making of Star Trek
, p. 165). You may be conflating it with a memo referring to first-season story editor John D.F. Black, whom he referred to as John "D.F." Black and jokingly accused of ripping off Dorothy Fontana's initials. I can't seem to find the page that one's on, though.
You are quite correct Christopher
, I definitely appear to have got those two instances mixed up in my mind. It shows how easily it can happen though, I suppose.