title: The Secret of NIMH
context: The Secret of NIMH is a 1982 American animated dark fantasy adventure film directed by Don Bluth in his directorial debut. It is an adaptation of Robert C. O'Brien's 1971 children's novel Mrs. Frisby and the Rats of NIMH. The film was produced by Aurora Productions and released by MGM/UA Entertainment Company for United Artists and features the voices of Elizabeth Hartman, Dom DeLuise, Arthur Malet, Derek Jacobi, Hermione Baddeley, John Carradine, Peter Strauss, and Paul Shenar. The "Mrs. Frisby" name in the novel had to be changed to "Mrs. Brisby" during production due to trademark concerns with Frisbee discs. It was followed in 1998 by a direct-to-video sequel called The Secret of NIMH 2: Timmy to the Rescue, which was made without Bluth's involvement or input. In 2015, a CGI/live action remake was reported to be in the works.[2]
question: When was the book The Secret of NIMH first published?
answers: 1982