Marco's Comments:
Tom Tucker's (of 6-cards repeat fame) course on a two-person code, very interesting, which he's used, with his wife Liz, for 25 years at the time of the writing.
The course comes with some extra material (a billet routine) laid in, including the "pledge of secrecy" signed by one Jerry Prin (?), but missing two audio tapes with a performance of the act.
From Herb Zarrow's auction.