The Rocky II novelization was written by Sylvester Stallone and published in 1979. There are some added details of the Rocky II story apparent in the novel but absent from the movie.
Differences from the movie
There is a minor character in the novel named Chink Weber, who hails from Jersey. This bears a striking resemblance to Chuck Wepner, the relatively unknown fighter who once went 15 rounds with Muhammad Ali. Wepner also hails from New Jersey and it is in this fight that Sylvester Stallone found his inspiration for the first Rocky movie. We also learn of Rocky's minor criminal offences. There is more detail of Paulie's involvement with Rocky's previous employer, Tony Gazzo.