In terms of the timeline of Asimov's so-called "greater Foundation series," there is one children's book which bridges the gap between the Robot series and the Empire series. Asimov published a children's book, "The Heavenly Host", in 1975. A slightly shorter version of this story was first published in "Boys' Life" magazine, December 1974. According to the book, this story takes place when humans are "spreading out through hundreds and thousands of worlds." Chronologically, this would place "The Heavenly Host" after "Robots and Empire" and before "The Stars, Like Dust." However, as this is a children's book and it involves an intelligent non-human species, it does not fit neatly into Asimov's Robot/Empire/Foundation universe, in which humans are the only intelligent species in the galaxy.