Author taxonomy

gistfile1.php

function register_taxonomies(){

  register_taxonomy('author', array('post'),
    array(
      'labels' => array(
        'name' => __( 'Authors' ),
        'singular_name' => __( 'Author' )
      ),
      'show_ui' => true,
      'query_var' => true
    )
  );

  register_taxonomy('book', array('post'),
    array(
      'labels' => array(
        'name' => __( 'Books' ),
        'singular_name' => __( 'Book' )
      ),
      'show_ui' => true,
      'query_var' => true
    )
  );
}

add_action( 'init', 'register_taxonomies', 0 );

/* Output */

$authors = get_the_terms($post->ID, 'author');
foreach($authors as $author){
    echo '<a href="' .get_term_link($author->slug, $taxonomy) .'">'.$author->name.'</a>';
}