Now that the "Faithful & Discreet Slave Class" has become essentially the Governing Body since 1919, almost every publication is obsolete and useless! (I know, they are useless)....
The FDS doctrine is a core teaching unique to Jehovah's Witnesses and now I believe they will have to change all of their understandings that are recorded in the Revelation Climax book, Ezekiel books---EVERY prophetic book written by the Society!