Robert A. Heinlein

A youth who has known only the primitive life of a galaxy slave is purchased by a beggar who turns out to be a man with many extracurricular activities.

Citizen of the Galaxy

Arron Kau

More mature than "Have Spacesuit" but still a good example of Heinlein's juvenile fiction.

Daryl Houston

Kind of neat at first (some of the world building on the Sisu in particular was neat), but it turned into a bit of a snooze and felt kind of half-formed. Read this aloud to the kids, who felt similarly meh about it.

Citizen of the Galaxy

Reviews