Question: Who had more pseudonyms, Robert Ludlum or Clement Greenberg?

Context paragraphs:
Helen Frankenthaler: Helen Frankenthaler (December 12, 1928 – December 27, 2011) was an American abstract expressionist painter.  She was a major contributor to the history of postwar American painting.  Having exhibited her work for over six decades (early 1950s until 2011), she spanned several generations of abstract painters while continuing to produce vital and ever-changing new work.  Frankenthaler began exhibiting her large-scale abstract expressionist paintings in contemporary museums and galleries in the early 1950s.  She was included in the 1964 "Post-Painterly Abstraction" exhibition curated by Clement Greenberg that introduced a newer generation of abstract painting that came to be known as Color Field.  Born in Manhattan, she was influenced by Greenberg, Hans Hofmann, and Jackson Pollock's paintings.  Her work has been the subject of several retrospective exhibitions, including a 1989 retrospective at the Museum of Modern Art in New York City, and been exhibited worldwide since the 1950s.  In 2001, she was awarded the National Medal of Arts.

Robert Ludlum bibliography: 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.

Combine painting: A combine painting is an artwork that incorporates various objects into a painted canvas surface, creating a sort of hybrid between painting and sculpture.  Items attached to paintings might include photographic images, clothing, newspaper clippings, ephemera or any number of three-dimensional objects.  The term is most closely associated with the artwork of American artist Robert Rauschenberg (1925–2008) who coined the phrase to describe his own creations.  Rauschenberg’s Combines explored the blurry boundaries between art and the everyday world.  In addition, his cross-medium creations challenged the doctrine of medium specificity mentioned by modernist art critic Clement Greenberg.  Frank Stella created a large body of paintings that recall the combine paintings of Robert Rauschenberg by juxtaposing a wide variety of surface and material in each work ultimately leading to Stella's sculpture and architecture of the 21st century.

Sidney Janis: Sidney Janis (July 8, 1896 – November 23, 1989) was a wealthy clothing manufacturer and art collector who opened an art gallery in New York in 1948.  His gallery quickly gained prominence, for he not only exhibited the work of most of the emerging leaders of Abstract Expressionism, but also that of such important European artists as Pierre Bonnard, Paul Klee, Joan Miró, and Piet Mondrian.  As the critic Clement Greenberg explained in a 1958 tribute to the dealer, Janis' exhibition practices had helped to establish the legitimacy of the Americans, for his policy "not only implied, it declared, that Jackson Pollock, Willem de Kooning, Franz Kline, Phillip Guston, Mark Rothko, and Robert Motherwell were to be judged by the same standards as Matisse and Picasso, without condescension, without making allowances."  Greenberg observed that in the late 1940s "the real issue was whether ambitious artists could live in this country by what they did ambitiously.  Sidney Janis helped as much as anyone to see that it was decided affirmatively."

The Bourne Supremacy: 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).

Robert Ludlum's The Bourne Conspiracy: 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.

Covert One: The Hades Factor: 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.

Clement Greenberg: Clement Greenberg ( ), occasionally writing under the pseudonym K. Hardesh (January 16, 1909 – May 7, 1994), was an American essayist known mainly as an influential visual art critic closely associated with American Modern art of the mid-20th century.  In particular, he is best remembered for his promotion of the abstract expressionist movement and was among the first published critics to praise the work of painter Jackson Pollock.

Robert Ludlum: 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.

Bourne (novel series): 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.

Supporting paragraphs: Robert Ludlum Clement Greenberg
Answer: Robert Ludlum