Silverberg, Robert, Threads of time; : three original novellas of science fiction, [electronic resource] / by Gregory Benford, Clifford D. Simak [and] Norman Spinrad. Edited and with an introd. by Robert Silverberg.. — [1st ed.]. — Nashville, : T. Nelson, [1974]. — 219 p. 22 cm.
Benford, G. Threads of time.--Simak, C. D. The marathon photograph.--Spinrad, N. Riding the torch.