odt_file = models.FileField(_('ODT file'), upload_to='books/odt', blank=True)
html_file = models.FileField(_('HTML file'), upload_to='books/html', blank=True)
odt_file = models.FileField(_('ODT file'), upload_to='books/odt', blank=True)
html_file = models.FileField(_('HTML file'), upload_to='books/html', blank=True)