Question: Who has more books published, Dan Masterson or Robert Ludlum?
Context: The Tristan Betrayal is a novel by Robert Ludlum, published posthumously in 2003.  Ludlum wrote an outline shortly before his death.  The novel itself was written by a ghostwriter. The Janson Directive is a novel by Robert Ludlum.  The posthumous novel was published in 2002, a year after Ludlum's death. The Bourne Supremacy is the second Jason Bourne novel written by Robert Ludlum, first published in 1986.  It is the sequel to Ludlum's bestseller "The Bourne Identity" (1980) and precedes Ludlum's final Bourne novel, "The Bourne Ultimatum" (1990). Bourne are a series of three novels by Robert Ludlum based on the fictional spy Jason Bourne.  The series has since been further extended by Eric Van Lustbader after the death of Robert Ludlum. The Bourne Ultimatum is the third Jason Bourne novel written by Robert Ludlum and a sequel to "The Bourne Supremacy" (1986).  First published in 1990, it was the last Bourne novel to be written by Ludlum himself.  Eric Van Lustbader wrote a sequel titled "The Bourne Legacy" fourteen years later. Covert One: The Hades Factor (a.k.a. "Robert Ludlum's Covert One: The Hades Factor", "The Hades Factor") is a made-for-TV thriller filmed in Toronto that first aired in 2006.  Directed by Mick Jackson, the miniseries is loosely based on "The Hades Factor", a 2000 novel written by Gayle Lynds as part of the Covert-One series created by Robert Ludlum. Dan Masterson (born February 22, 1934) is an American poet born in Buffalo, New York, United States (US).  He became a poet after several jobs as an actor, narrator, disc jockey (DJ), lay missionary worker, advertising copywriter, and theatrical public relations director. Robert Ludlum's The Bourne Conspiracy (known as simply The Bourne Conspiracy) is a third-person action stealth video game developed by High Moon Studios and published by Sierra Entertainment for the PlayStation 3 and Xbox 360.  The game expands upon Robert Ludlum's character Jason Bourne, and immerses the player in a cat and mouse style espionage action adventure.  The game was released in North America on June 3, June 5 in Australia and June 27, 2008 in Europe. Robert Ludlum (1927–2001) was an American author of twenty-seven novels between 1971 and 2006, the last being issued five years after his death.  Of his twenty-seven novels, two were originally published under the pseudonym of Jonathan Ryder and another under the pseudonym of Michael Shepherd.  Ludlum also created the "Covert-One" series, overseeing the first three novels with Gayle Lynds and Philip Shelby before his death.  Following Ludlum's death, his estate has continued to publish novels under his name with eight authors having written a combined twenty-two novels under the Ludlum brand, a trademark inscription of "Robert Ludlum's" on every book (e.g. "Robert Ludlum's The Bourne Dominion").  Since 2007, publishing rights in the United States have been held by Grand Central Publishing, taking over from St. Martin's Press who held the rights from 2000 to 2006. Robert Ludlum (May 25, 1927 – March 12, 2001) was an American author of 27 thriller novels, best known as the creator of Jason Bourne from the original "The Bourne Trilogy" series.  The number of copies of his books in print is estimated between 290 million and 500 million.  They have been published in 33 languages and 40 countries.  Ludlum also published books under the pseudonyms Jonathan Ryder and Michael Shepherd.
Answer: Robert Ludlum