Sentinels: A collection of stories and essays by some of Clarke's many colleagues and friends who were influenced by his writings and thoughts about human possibilities, and who continue as his sentinels by the doors to the future that he opened... Stories and essays by: Isaac Asimov, Stephen Baxter, Gregory Benford, Russell Blackford, Damien Broderick, Pat Cadigan, Sheila Finch, James Gunn, Robert A. Heinlein, A.A. Jackson IV, Christopher McKitterick, Charles Pellegrino, Frederik Pohl, Pamela Sargent, Joan Slonczewski, Allen Steele, Howard Waldrop, Jack Williamson, George Zebrowski.