title: Is there any good gem to bookmark record of particular model?
body: <p>I have 3 models such as User model,Book model, and Author model.  </p>
  
  <p>I'd like to implement the function with which, User can bookmark record of Books or Authors as
  their favorite.  </p>
  
  <p>Is there any good gem to do this easily???  </p>
  
  <p>I'm not thinking of making on my own.</p>