Original: City of Illusions was republished in 1978 along with Rocannon's World and Planet of Exile in a volume called Three Hainish Novels and in 1994 with the same novels in Worlds of Exile and Illusion.
Simplified: City of Illusions was republished in 1978 with Rocannon's World and Planet of Exile in a set called Three Hainish Novels and in 1994 with the same books in Worlds of Exile and Illusion.