Sixth Column

Sixth Column, also known under the title The Day After Tomorrow, is a science fiction novel by American writer Robert A. Heinlein, based on a story by editor John W. Campbell, and set in a United States that has been conquered by the PanAsians, who are asserted to be neither Japanese nor Chinese.
Originally published as a serial in Astounding Science Fiction (January, February, March 1941, using the pen name Anson MacDonald), it was published in hardcover in 1949.

Robert A. Heinlein. Sixth Column. New York: Gnome Press, [1949]. First edition. Octavo. 256 pages.