Complex sentence: Spiegelman was sure the film, "An American Tail" (1986), was inspired by "Maus" and became eager to have his unfinished book come out before the movie to avoid comparisons.
Split into simpler sentences: Spiegelman was sure the film, "An American Tail" (1986), was inspired by "Maus". He became eager to have his unfinished book come out before the movie to avoid comparisons.