- book_tag = get_object_or_404(models.Tag, slug='l-' + book_slug)
- theme = get_object_or_404(models.Tag, slug=theme_slug)
+ book_tag = get_object_or_404(models.Tag, slug='l-' + book_slug, category='book')
+ theme = get_object_or_404(models.Tag, slug=theme_slug, category='theme')