Future Historical References

After Such Knowledge (ASK), Volumes I and II
I, Doctor Mirabilis: Roger Bacon, founder/discoverer of scientific method, is possibly inspired by a demon.
IIa, Black Easter: twentieth century magicians conjure major demons, causing Armageddon.
IIb, The Day After Judgment: after Armageddon.

The Haertel Scholium
Welcome To Mars: Haertel on Mars.
"No Jokes On Mars": later on Mars.
"Common Time": Haertel and Garrard.
"Nor Iron Bars": after the Haertel overdrive, tested by Garrard, the Arpe drive.
"This Earth of Hours": after the Arpe drive, the Standing Wave.

The Star Dwellers: a version of the Haertel overdrive that is a Standing Wave.
Mission To The Heart Stars: sequel; references to Garrard and to the Centaurians that he encountered.
"A Dusk of Idols": references to the star-dwelling Angels and to the Heart Stars.

The Quincunx Of Time: the Haertel overdrive; a planet named after Hammersmith, who traveled with Arpe; Dirac messages from the futures described in the two subsequent works.
"A Style in Treason": the Imaginary Drive, an auctorial comment on Haertel's and other FTL drives.
Midsummer Century: reference to Thor Wald, inventor of the Dirac communicator.

ASK, Vol III/The Haertel Scholium
III, A Case Of Conscience: a Haertel overdrive future with a theological or demonological problem.

Comments
This sequence is not linear. Armageddon is not necessarily a discontinuity because its effects are reversed at the end of ASK, IIb. However, four futures diverge although they are directly or indirectly linked by references to Haertel.

These four futures culminate in:

conflict between the Terrestrial Matriarchy and the telepathic Central Empire;
conflict between the UN/Angels alliance and the Heart Stars;
an expanding intergalactic civilization based on a monopoly of prescience while civilizations guided by higher mental states rise and fall on Earth;
the problem posed by the Lithians.