public ActionResult Reviews(string isbn)
        {
            AccessToken accessToken = ((AccessToken)Session["AccessToken"]);

            ViewBag.ISBN = isbn;
            List <ReviewDesc> reviews = reviewManager.GetReviewListByISBNDesc(isbn, Active.active);

            if (reviews.Count == 0)
            {
                ModelState.AddModelError("", "There are no reviews for this book");
            }
            return(View(reviews));
        }