Human as Machine Analog: ... the Fiction of Robert A. Heinlein
Gaar, Alice Carol. "The Human as Machine Analog: The Big Daddy of Interchangeable Parts in the Fiction of Robert A. Heinlein." Robert A. Heinlein. Joseph D. Olander and Martin Harry Greenberg, eds. New York: Taplinger, 1980.
Deals with Heinlein's response to "a cosmos that might really be just a gigantic computer" (265).