如何在DJango管理界面中显示ForeignKey反向查找列表？

I have a couple of models:

我有几个型号：

class Customer(models.Model):
    customer_name = models.CharField(max_length=200)

    def __unicode__(self):
        return self.customer_name

    class Meta:
        ordering = ('customer_name',)

class Unit(models.Model):
    unit_number = models.IntegerField()
    rentable = models.BooleanField()
    owner = models.ForeignKey(Customer, related_name='units', blank=True, null=True)

    def __unicode__(self):
        return str(self.unit_number)

    class Meta:
        ordering = ('unit_number',)
class Cu