Franklin, H. Bruce. Robert A. Heinlein: America as Science Fiction. New York: Oxford, 1980. The most recent booklength study of Heinlein's work.

Franklin divides Heinlein's creative output into five stages, but devotes little attention to the juvenile series.

Olander, Joseph D., and Martin Harry Greenberg. Robert A. Heinlein. New York: Taplinger, 1978. A collection of critical essays, this book contains an excellent overview of the juvenile series.

Panshin, Alexei. Heinlein in Dimension. Chicago: Advent, 1976. The first booklength study of Heinlein's work; highly subjective, but influential on all later studies.

Parkin-Speer, Diane. "Robert A. Heinlein: The Novelist as Preacher." Extrapolation 20 (Fall 1979): 214-222.

Traces the decline of Heinlein's work from the early novels to his complex work of the 1970s.

Slusser, George Edgar. The Classic Years of Robert A. Heinlein. San Bernardino: Borgo Press, 1977. Detailed study of Heinlein's early work. Sees his social elitism as essentially Calvinist in...