protected void Page_Load(object sender, EventArgs e)
        {
            String isbn = Session[Constants.ISBN].ToString();


            //if (!IsPostBack)
            //{
            // Session[Constants.ISBN].ToString();
            if (isbn != null)
            {
                Book b = BookModel.GetBookByISBN(isbn);
                Label_Author.Text        = b.Author.AuthorName;
                Label_Title.Text         = b.Title;
                Label_Category.Text      = b.Category.CategoryName;
                Label_ISBN.Text          = b.ISBN;
                Label_Price.Text         = b.Price.ToString();
                Label_Discount.Text      = b.DiscountedPrice.ToString();
                Label_Synopsis.Text      = b.Synopsis;
                Image_BookImage.ImageUrl = "~/Resources/BookCovers/" + isbn.ToString() + ".jpg";

                List <Book> list = BookModel.GetBooksByCategory(b.Category);
                DataList1.DataSource = list;
                DataList1.DataBind();

                //}
            }
        }