<?php
$all_books = get_terms( 'history_books' ); // Get all history book terms.
$rand_book = $all_books[ array_rand( $all_books ) ]; // Select one at random.
$related = get_posts(
array(
'posts_per_page' => 5,
'tax_query' => array(
array(
'taxonomy' => 'history_books',
'terms' => array( $rand_book->term_id ),
)
)
)
);
?>
<h3>
<a href="https://wordpress.stackexchange.com/questions/104280/<?php echo get_term_link( $rand_book ) ?>">
<img src="/path/to/images/terms_hsb<?php echo $rand_book->term_id ?>.jpg" alt="<?php echo esc_attr( $rand_book->name ) ?>" />
<?php echo esc_html( $rand_book->name ) ?>
</a> (<?php echo $rand_book->count ?>)
</h3>
<?php if ( $related ) : ?>
<ul class="related">
<?php foreach ( $related as $post ) : setup_postdata( $post ) ?>
<li><a href="https://wordpress.stackexchange.com/questions/104280/<?php the_permalink(); ?>"><?php the_title(); ?></a></li>
<?php endforeach ?>
</ul>
<?php endif ?>
