I have different chapters from coauthors to include in our final manuscript, and I can't use Mendeley or Zootero to unify the style of references ? What should I do ?!
Since you don't mention what typesetting software you are using, it's hard to say. Personally, with all the math I'm using, the only thing I can use is LaTeX together with the reference management system BiBTeX - it's a marvellous tool, making the resulting reference list always uniform in style.