Nine Suns was one of two books of poetry written by Hikaru Sulu's father Hosato Sulu by the mid-23rd century, the other being Fire in Frost.
In 2264, when Sulu's fencing opponent called him an "illiterate peasant" after losing to him, he reflected that her parents, if they had literary pretensions, probably had a copy of Fire in Frost or Nine Suns in their library. (TOS novel: Enterprise: The First Adventure)