In a novel that I am presently writing, a sequel to four other novels, I have my characters try to discover the true model for James Hiltons's Shangri-La. Each character is looking for inspiration and hope a few months after the horror of September 11, 2001.

From whom do I get permission to refer to James Hilton's "Lost Horizon" and to his Utopian society, Shangri-La? When I complete the novel, I have to ensure that I get permission to mention any previously copyrighted material. What I am doing is similar to what was done in "Sleepless in Seattle" when "A Love Affair to Remember" is cited.