Time Travel In Future Histories

(i) I do not accept Time Enough For Love as an addition to Heinlein's Future History.

(ii) Olaf Stapledon's Last Men time travel mentally and one narrates the history.

(iii) In Poul Anderson's There Will Be Time, time travelers visit the period of the Maurai History.

(iv) In Larry Niven's Known Space future history:

"'...that funny religion on Altair One. They thought they could travel in time.'
"Yes sir. When we landed the infantry they were all gone.'
"'They must have all committed suicide with disintegrators.'"
-Larry Niven, "The Warriors" IN Niven, Tales Of Known Space (New York, 1975), pp. 135-151 AT p. 145.