Question: What occupation did Robert E. Howard and Robert A. Heinlein share?

Context paragraphs:
Conan: Adventures in an Age Undreamed Of: Robert E. Howard's Conan: Adventures in an Age Undreamed Of, or simply Conan: Adventures in an Age Undreamed Of, is a sword and sorcery British pen-and-paper role-playing game set in the world of Conan the Barbarian, the fictional Hyborian Age.  Both the character and the setting were first imagined by American author Robert E. Howard (1906-1936) as of 1932 and until his suicide in 1936.  Howard's original literary work has since spawned a vast franchise of novels, comic books, films, video games, board games, role-playing games, etc.  Following this tradition, "Conan: Adventures in an Age Undreamed Of" is the third officially licensed Conan role-playing game.  The two precedent games were "Conan Role-Playing Game" (1985-1988) and "" (2004-2010), although there also had been supplements for independent generic systems, like "GURPS Conan" (1988-1989).

Red Planet (novel): Red Planet is a 1949 science fiction novel by Robert A. Heinlein about students at boarding school on the planet Mars.  It represents the first appearance of Heinlein's idealized Martian elder race (see also "Stranger in a Strange Land").  The version published in 1949 featured a number of changes forced on Heinlein by Scribner's, since it was published as part of the Heinlein juveniles.  After Heinlein's death, the book was reissued by Del Rey Books as the author originally intended.

Robert E. Howard: Robert Ervin Howard (January 22, 1906 – June 11, 1936) was an American author who wrote pulp fiction in a diverse range of genres.  He is well known for his character Conan the Barbarian and is regarded as the father of the sword and sorcery subgenre.

Robert A. Heinlein: Robert Anson Heinlein ( ; July 7, 1907 – May 8, 1988) was an American science fiction writer.  Often called the "dean of science fiction writers", his sometimes controversial works continue to have an influential effect on the genre, and on modern culture more generally.

Heinlein juveniles: Heinlein juveniles are the novels written by Robert A. Heinlein aimed for what would now be known as the "young adult" market.  The core group are the twelve Heinlein novels published by Scribner's between 1947 and 1958.  A thirteenth, "Starship Troopers", was submitted to Scribner's but rejected and instead published by Putnam.  A fourteenth novel, "Podkayne of Mars", is often listed as a "Heinlein juvenile", although Heinlein himself did not consider it to be one.

Legacy of Robert E. Howard: Robert E. Howard's legacy extended after his death in 1936.  Howard's most famous character, Conan the Barbarian, has a pop-culture imprint that has been compared to such icons as Tarzan of the Apes, Count Dracula, Sherlock Holmes, and James Bond.  Howard's critical reputation suffered at first but over the decades works of Howard scholarship have been published.  The first professionally published example of this was L. Sprague de Camp's "Dark Valley Destiny" (1983) which was followed by other works, including Don Herron's "The Dark Barbarian" (1984) and Mark Finn's "" (2006).  Also in 2006, a charity, Robert E. Howard Foundation, was created to promote further scholarship.

A Robert Heinlein Omnibus: A Robert Heinlein Omnibus was a second collection of Robert A Heinlein's stories to use the term "omnibus" the first being The Robert Heinlein Omnibus (1958), published in 1966.  Containing fifteen of Heinlein's short stories and novellas, this second "Omnibus" represents a short chronological period, 1940 to 1950, of Heinlein's writings.

Valeria (Conan the Barbarian): Valeria is a pirate and adventuress (a member of "The Red Brotherhood" of pirates) in the fictional universe of Robert E. Howard's Conan the Barbarian stories.  She appears in Robert E. Howard's Conan novella "Red Nails", serialized in "Weird Tales" 28 1-3 (July, August/September & October 1936).  This was the last Conan story written by Howard, and published posthumously.  The name was also used for Conan's love interest in the 1982 film "Conan the Barbarian".

Free Men: "Free Men" is a science fiction short story by Robert A. Heinlein, which originally appeared in the Heinlein collection, "The Worlds of Robert A. Heinlein" (Ace F-375, 1966) and was later collected in "Expanded Universe".  It is copyrighted by Heinlein in 1966, but was probably written between 1947 and 1950, judging from the foreword to it in "Expanded Universe", which mentions that it was written after "Rocket Ship Galileo".

Expanded Universe (book): Expanded Universe is a 1980 collection of stories and essays by Robert A. Heinlein.  In full, its title is Expanded Universe, The New Worlds of Robert A. Heinlein.  The trade paperback 1981 edition lists the subtitle under other Heinlein books as "More Worlds of Robert A. Heinlein" because the contents subsume the 1966 Ace Books collection, "The Worlds of Robert A. Heinlein".  The current volume is dedicated to William Targ.

Supporting paragraphs: Robert E. Howard Robert A. Heinlein
Answer: writer