 A Kzin character, Speaker-to-Animals (later known as Chmeee), subsequently played a major role in Niven's Hugo and Nebula award-winning "Ringworld" (1970) and "Ringworld Engineers" (1980), giving considerably more background of the Kzinti and their interactions with human civilizations.Following "Ringworld", Niven gave permission to several friends to write stories taking place in the time following "The Warriors" but before "The Soft Weapon"; these stories (including a handful by Niven) were collected in a number of volumes of "The Man-Kzin Wars", which eventually reached fourteen volumes, the first published in June 1988.Kzinti also appear in "Juggler of Worlds" (2008) and "Fate of Worlds" (2012), novels within the Fleet of Worlds series (cowritten with Edward M. Lerner).