Guardian Angel was first published in the April 1950 issue of Famous Fantastic Mysteries. It was later expanded to become the first part of the classic novel, Childhood's End. Sir Arthur C. Clarke (1917-2008) is regarded as one of the most-influential science fiction writers of all time. He was named a Grand Master by the Science Fiction and Fantasy Writers of America, and was inducted into the Science Fiction and Fantasy Hall of Fame.

"Second Dawn" was first published in the August 1951 issue of Science Fiction Quarterly. Sir Arthur C. Clarke (1917-2008) is regarded as one of the most-influential science fiction writers of all time. He was named a Grand Master by the Science Fiction and Fantasy Writers of America, and was inducted into the Science Fiction and Fantasy Hall of Fame.

"The Lion of Comarre" was first published in the August 1949 issue of Thrilling Wonder Stories. Sir Arthur C. Clarke (1917-2008) is regarded as one of the most-influential science fiction writers of all time. He was named a Grand Master by the Science Fiction and Fantasy Writers of America, and was inducted into the Science Fiction and Fantasy Hall of Fame.

"Jupiter Five" was first published in the May 1953 issue of If. Sir Arthur C. Clarke (1917-2008) is regarded as one of the most-influential science fiction writers of all time. He was named a Grand Master by the Science Fiction and Fantasy Writers of America, and was inducted into the Science Fiction and Fantasy Hall of Fame.

"Critical Mass" was first published in the August 1957 issue of Space Science Fiction Magazine. Sir Arthur C. Clarke (1917-2008) is regarded as one of the most-influential science fiction writers of all time. He was named a Grand Master by the Science Fiction and Fantasy Writers of America, and was inducted into the Science Fiction and Fantasy Hall of Fame.