Question: What type of publication does Len Deighton and Margaret Landon have in common?

Context articles: Len Deighton's London Dossier
Faith (novel)
Winter (Deighton novel)
Fighter: The True Story of the Battle of Britain
Hope (novel)
Margaret Landon
Harry Palmer
Len Deighton
Bullet to Beijing
Len Deighton's Action Cook Book

Len Deighton's London Dossier is a guide book to London, edited by British author Len Deighton and published in 1967.
 It consists of a ""collection of personal guides to the hidden gems and sites of London by a range of writers and raconteurs, many of them Len Deighton’s friends.""
 Deighton himself contributes two of the 14 essays.
Faith is a 1994 spy novel by Len Deighton.
 It is the first novel in the final trilogy of three about Bernard Samson, a middle-aged and somewhat jaded intelligence officer working for the British Secret Intelligence Service (MI6).
 "Faith" is part of the "Faith, Hope and Charity" trilogy, being followed by "Hope" and "Charity".
 This trilogy is preceded by the "Game, Set and Match" and the "Hook, Line and Sinker" trilogies.
 Deighton's novel "Winter" (1987) is a prequel to the nine novels, covering the years 1900-1945 and providing the backstory to some of the characters.
Winter is a 1987 novel by Len Deighton, which follows the lives of a German family from 1899 to 1945.
 At the same time the novel provides an historical background to several of the characters in Deighton's nine novels about the British intelligence agent Bernard Samson, who grew up in the ruins of Berlin after World War II.
Fighter: The True Story of the Battle of Britain (ISBN  ) is a Second World War military history book by English author Len Deighton.
 First published in 1977, "Fighter" was Deighton's first history book, he having made his name as a writer of spy fiction.
 Deighton was encouraged to write the book by his friend, the British historian A.J.P. Taylor, who wrote the introduction to "Fighter".
Hope is a 1995 spy novel by Len Deighton.
 It is the second novel in the final trilogy of three about Bernard Samson, a middle-aged and somewhat jaded intelligence officer working for the British Secret Intelligence Service (MI6).
 "Hope" is part of the "Faith, Hope and Charity" trilogy, being preceded by "Faith" and followed by "Charity".
 This trilogy is preceded by the "Game, Set and Match" and the "Hook, Line and Sinker" trilogies.
 Deighton's novel "Winter" (1987) is a prequel to the nine novels, covering the years 1900-1945 and providing the backstory to some of the characters.
Margaret Landon (September 7, 1903 – December 4, 1993) was an American writer best remembered for "Anna and the King of Siam", her best-selling 1944 novel of the life of Anna Leonowens which eventually sold over a million copies and was translated into more than twenty languages.
 In 1950, Landon sold the musical play rights to Richard Rodgers and Oscar Hammerstein II, who created the musical "The King and I" from her book.
 A later work, "Never Dies the Dream", appeared in 1949.
Harry Palmer is the protagonist of a number of films based on the unnamed main character from the spy novels written by Len Deighton.
 Michael Caine played Harry Palmer in three of the four films based on the four published novels featuring this character.
 Caine also starred as this character in two other films not directly based on Deighton's novels.
Leonard Cyril Deighton ( ; born 18 February 1929), known as Len Deighton, is a British author.
 Deighton is considered one of the top three spy novelists of his time (along with Ian Fleming and John le Carré).
 In addition he is a highly acclaimed military historian, cookery writer, and graphic artist. "
The IPCRESS File" (1962), his first novel, was an instant bestseller and broke the mould of thriller writing. "
The Sunday Times" called him "the poet of the spy story".
 Deighton’s first protagonist – a nameless spy christened Harry Palmer in the films – was made famous worldwide in 1960s films starring Michael Caine.
Bullet to Beijing is a 1995 made-for-television film that continues the adventures of the fictional spy Harry Palmer, who appeared in the 1960s films "The Ipcress File", "Funeral in Berlin" and "Billion Dollar Brain", based on books by author Len Deighton.
 Though an alternate title is "Len Deighton's Bullet to Beijing", Deighton was not associated with the film at all.
Len Deighton's Action Cook Book is a 1965 collection of cookery strips (known as a cookstrip, an invention on Len Deighton's from his days as a student at the Royal College of Art) originally published in the "Observer" newspaper, with additional information and notes.
 Aimed at ""an audience of men unskilled at knowing their way around the kitchen"", the book has been described as a cult classic from the period and helped pave the transition from cooking being only for women, into bring a sophisticated expectation of a modern man.