filter.py

class CitedBooksFilter(SimpleListFilter):
  title = _('cited book')
  parameter_name = 'book_title'

  def lookups(self, request, model_admin):
    return Citation.objects.exclude(cited_book_id=None).values_list('id', 'title').distinct()

  def queryset(self, request, queryset):
    if self.value():
      queryset = queryset.filter(cited_book_id=self.value())
    return queryset