Question: Marion Zimmer Bradley and Robin McKinley, are of which nationality?

full_context: Document 1: Carolyn Sherwin Bailey: Carolyn Sherwin Bailey (October 25, 1875 – December 23, 1961) was an American children's author. She was born in Hoosick Falls, New York and attended Teachers College, Columbia University, from which she graduated in 1896. She contributed to the "Ladies' Home Journal" and other magazines. She published volumes of stories for children like methods of story telling, teaching children and other related subjects, which include "Boys and Girls of Colonial Days" (1917); "Broad Stripes and Bright Stars" (1919); "Hero Stories" (1919); and "The Little Rabbit Who Wanted Red Wings" (1945). She wrote "For the Children's Hour" (1906) in collaboration with Clara M. Lewis. In 1947, her book "Miss Hickory" won the Newbery Medal.
Document 2: The Spell Sword: The Spell Sword is a sword and planet novel by American writer Marion Zimmer Bradley, part of the Darkover series. The book was co-authored by Paul Edwin Zimmer, Bradley's brother, though he was not credited. "The Spell Sword" was first published in paperback by DAW in 1974 OCLC 156484864  and has been republished several times.
Document 3: The Blue Sword: The Blue Sword is a fantasy novel written by American author Robin McKinley and published by Greenwillow Books in 1982. The novel "The Hero and the Crown" serves as a prequel. "The Blue Sword" has received several awards, including: Newbery Honor Award, ALA Best Book for Young Adults and the ALA Notable Children's Book. The story, told in the third-person omniscient perspective, is of a young woman named Angharad Crewe, called Harry, who becomes a warrior in her adopted homeland of Damar.
Document 4: Marion Zimmer Bradley's Darkover: Marion Zimmer Bradley's Darkover is a collection of science fantasy short stories by American writer Marion Zimmer Bradley. The stories are set in Bradley's world of Darkover. The book was first published by DAW Books (No. 929) in October, 1993.
Document 5: A Knot in the Grain and Other Stories: A Knot in the Grain and other Stories is a collection of short fantasy stories by author and Newbery Medalist, Robin McKinley. Published by HarperTrophy, this collection of stories came out in 1994 although several of the stories had been previously printed. This collection gives readers a taste of McKinley's style and allows brief glimpses in the worlds where magic lives and you never know what might be possible.
Document 6: Robin McKinley: Jennifer Carolyn Robin McKinley (born November 16, 1952), known as Robin McKinley, is an American author of fantasy and children's books. Her 1984 novel "The Hero and the Crown" won the Newbery Medal as the year's best new American children's book.
Document 7: Gail Carson Levine: Gail Carson Levine (born September 17, 1947) is an American author of young adult books. Her first novel, "Ella Enchanted", received a Newbery Honor in 1998.
Document 8: Marion Zimmer Bradley's Fantasy Magazine: Marion Zimmer Bradley's Fantasy Magazine was a quarterly fantasy magazine founded and initially edited by fantasy and science fiction author Marion Zimmer Bradley. Fifty issues appeared from summer 1988 through December 2000. It was published by MZB Enterprises from 1988-1989, Marion Zimmer Bradley Ltd. from 1990-1993, and the Marion Zimmer Bradley Living Trust from 1994-2000, all based in Berkeley, California. The Trust continued publication for a short time after Bradley's death in 1999; the magazine went out of business at the end of 2000.
Document 9: Sword and Sorceress series: The "Sword and Sorceress" series is a series of fantasy anthologies originally edited by Marion Zimmer Bradley, and originally published by DAW Books. As she explained in the foreword to the first volume, she created the anthology to redress the lack of strong female protagonists in the subgenre of sword and sorcery. At the time, most female characters in sword and sorcery were little more than stock damsels in distress, or pawns who were distributed at the conclusion of the story as "bad-conduct prizes" (Bradley's term) for the male protagonists. Many of the early sword-and-sorcery works featured attitudes toward women that Bradley considered appalling.
Document 10: Chalice (novel): Chalice is a novel by American fantasy author Robin McKinley. It was published in 2008 (New York: G. P. Putnam's Sons).
Document 11: E. L. Konigsburg: Elaine Lobl Konigsburg (February 10, 1930 – April 19, 2013) was an American writer and illustrator of children's books and young adult fiction. She is one of six writers to win two Newbery Medals, the venerable American Library Association award for the year's "most distinguished contribution to American children's literature."
Document 12: Marion Zimmer Bradley: Marion Eleanor Zimmer Bradley (June 3, 1930 – September 25, 1999) was an American author of fantasy, historical fantasy, science fiction, and science fantasy novels, and is best known for the Arthurian fiction novel "The Mists of Avalon", and the Darkover series. While some critics have noted a feminist perspective in her writing, her popularity has been posthumously marred by multiple accusations against her of child sexual abuse and rape by two of her children, Mark and Moira Greyland, among many others. Zimmer Bradley's first child, David R. Bradley, and her brother, Paul Edwin Zimmer, also became published science fiction and fantasy authors.
Document 13: The Forest House: The Forest House is a fantasy novel by American writers Marion Zimmer Bradley and Diana L. Paxson, though the latter is uncredited by the publisher. It is a prequel to Bradley's Arthurian novel "The Mists of Avalon".
Document 14: Robin Hobb: Robin Hobb is the pen name of Margaret Astrid Lindholm Ogden (born March 5, 1952), an American writer. She is best known for the books set in the Realm of the Elderlings, which started in 1995 with the publication of "Assassin's Apprentice", the first book in the Farseer trilogy.
Document 15: Darkover series: The Darkover series is a science fiction-fantasy chronology consisting of several novels and short stories set in the fictional world of Darkover as created by author Marion Zimmer Bradley. The word "Darkover" is a registered trademark owned by the Marion Zimmer Bradley Literary Works Trust.
ground_truth: American