Asimov's Robot Novels and the Two Non-Series Novels
Hassler, Donald M. "Asimov's Robot Novels and the Two Non-Series Novels." Foundation #37 (Autumn 1986): 22-30.
The robot novels here are The Caves of Steel and The Naked Sun (q.v. under Fiction Category); the non-series novels are The End of Eternity and The Gods Themselves. See for the robot novels' Elijah Baley's "open and loose" curiosity vs. his robot partner's "machine-like rejection" of such inefficiency (24) and for DMH's discussion of "gold," (for Earth's "Medievalists") vs. the Spacer's "carbon," and "iron"—primarily humans/robots (24-25).