Joe,
Take a look at the following thread, which is what led to the
B2 page being updated to 1980 by Foulfoot:
B2 First printing date. Source?Short answer is that Frank Mentzer started working in Jan 1980, and he worked on the module, so there's no way that it came out in 1979. The Holmes Basic set page should probably be annotated to note that while the rulebook is dated Dec 1979, versions of the set with B2 could not have been released until 1980.
You can see a longer version of Frank's story here (formerly on the Eldritch Enterprises site, now archived on the Internet Archive):
https://web.archive.org/web/20140326234 ... /ouat.aspxZ
Zenopus Archives
website &
blog: Exploring the Underworld of Holmes Basic D&D.
Holmes Ref: Reference Sheets for Holmes Basic Referees, also compatible with OD&D plus the Greyhawk supplement