class Publisher(models.Model):
    name = models.CharField(max_length=30)
place = models.OneToOneField(Place, primary_key=True)


class Author(models.Model):
    first_name = models.CharField(max_length=30)
last_name = models.CharField(max_length=40)


class Book(models.Model):
    title = models.CharField(max_length=100)
publisher = models.ForeignKey(Publisher)
authors = models.ManyToManyField(Author)
Django OneToOneField, ManyToManyField, Foreign Key