In the current century, publishers have brought out previously unseen material by Robert Heinlein.
Some of it is simply alternate versions of familiar novels, such as Podkayne of Mars, The Puppet Masters, Red Planet, and Stranger in a Strange Land.
But we’ve also see works that he didn’t publish, but that he later quarried for the material of later works: For Us, the Living, which supplied a secondary character to Beyond This Horizon and several thematic elements to the Future History, and The Pursuit of the Pankera, which was radically rewritten to give us The Number of the Beast.
With the compilation of the Virginia Edition, not only all of Heinlein’s previously published works have been made available, but various less known ones, such as decades of his letters. Among these are various ventures into scriptwriting for movies and television. Destination Moon is well known, but his proposals for television series were never produced, and only with the Virginia Edition have they become available.
The last of these, Century XXII, was mainly worked on in 1963, and he abandoned it in 1964 after clashes with Howie Horowitz, who proposed the project to him. After that, Heinlein gave up on writing for film and television as a waste of time. But Century XXII casts some light onto Heinlein’s later writing, and especially onto The Moon Is a Harsh Mistress, generally regarded as one of his best novels and more specifically as the prototype of libertarian science fiction.