Three Fictional Histories

JRR Tolkien devoted much of his life to the History of Middle Earth with what results we know. By contrast, Robert Heinlein's Future History is only a small part of his total output. Poul Anderson's Technic History, although much longer than the Future History, is also of necessity much shorter than Tolkien's Middle Earth canon.

Heinlein and Anderson achieve future historical continuity with very few cross-references, e.g.:

Pinero appears in "Lifeline" and is mentioned in Methuselah's Children;

Rhysling appears in "The Green Hills of Earth" and is mentioned in perhaps three other works (and also makes it into Anderson's Old Phoenix);

Anderson deploys a few surnames - Runeberg, Holm and Davisson in just two works each. (See Families In Future Histories.)

Nevertheless, both Heinlein and Anderson achieve the desired effect: credible fictional (future) histories.