private void Author_Click(object sender, RoutedEventArgs e)
        {
            var context = new BookCardsViewModel(Model.Content.ByAuthor,
                                                 ((Hyperlink)sender).NavigateUri.ToString());

            DataContext = context;
        }
        public BookCards(Content content = Model.Content.All)
        {
            InitializeComponent();
            var context = new BookCardsViewModel(content);

            DataContext = context;
        }