Apple developer documentation. Issues 8 to 13 of develop did not include a specific CD but instead included that months Apple Developer CD Series disc.
http://preserve.mactech.com/articles/develop/issue_14/002-003_Editorial....
I'd like to talk about a change that you've no doubt already noticed: printed develop is no longer accompanied by the Developer CD Series disc, but instead comes with its own CD as in days of old. Yes, we've come full circle: develop had its own CD for Issues 1 through 7; then, starting with Issue 8, it was accompanied by the Developer CD Series disc, which offered a superset of the contents of develop's own CD. The Developer CD is actually a monthly CD that's mailed to members of Apple's developer programs and to subscribers to the Apple Developer Mailing (formerly the APDA Technical Information Mailing). At the time, it seemed simpler and more beneficial all around to just take every third Developer CD and make it the CD that accompanies develop.
develop 8, Volume X, On a clear day You can CD forever
develop 9, Feb-92, 20,000 Leagues Under the CD
develop 10, May-92, The Byte Stuff
develop 11, Aug-92, Hack to the Future
develop 12, Dec-92, Wayne's Gworld
develop 13, Mar-93, Other People's Memory