鋼鉄都市
"The Portable Star" was accompanied in the Winter 1955 issue of "Thrilling Wonder Stories" with a timeline of the Foundation series which included the story, along with a number of others. The timeline does not include any of the stories from "I, Robot", as well as the novel "The Caves of Steel", since at this time Asimov considered the "Robot" series separate from the "Foundation" series.