{% for author in book.authors %}
<div class="white-box">
<a style="display:block" href="{{ author.get_absolute_url }}">
- {% cache 86400 catalogue_tag_box rel.pk %}
+ {% cache 86400 catalogue_tag_box author.pk %}
{% include 'catalogue/tag_box.html' with tag=author %}
{% endcache %}
</a>