ACF repeater with nested relationship field, used in widget for ACF Widgets plugin integration (http://acfwidgets.com/). Used on http://julialondon.com/about/ in sidebar to display featured books.

widget-featured-books.php

<?php 
  if (have_rows('book_features', $acfw)) {
    $features = get_field('book_features', $acfw);
    $count = count($features);
    echo '<div class="widget-features count-' . $count . ' cf">';
        while ( have_rows('book_features', $acfw) ) { the_row();
            $headline = get_sub_field('headline', $acfw);
            $sub_head = get_sub_field('sub_head', $acfw);
            $cta = get_sub_field('cta_text', $acfw);
            $feature_link = '';
            if ( get_sub_field('feature_link', $acfw) ) {
                $feature_link = get_sub_field('feature_link', $acfw);
            }
            if (get_sub_field('featured_book', $acfw)) {
                $books = get_sub_field('featured_book', $acfw); ?>
                <?php foreach( $books as $book ) { 
                    $img_attr = array(
                        'title' => trim( strip_tags(  $headline ) ),
                    );
                    if ($feature_link == '') {
                        $feature_link = get_permalink( $book->ID );
                    }
                    ?>
                    <div class="widget-block">
                        <a href="<?php echo $feature_link; ?>"><?php echo get_the_post_thumbnail( $book->ID, 'thumbnail', $img_attr ); ?></a>
                        <h3 class="widget-block-title"><a href="<?php echo $feature_link; ?>"><?php echo $headline; ?></a></h3>
                        <?php if ($sub_head) { ?><span class="widget-block-subtitle"><?php echo $sub_head; ?></span><?php } ?>
                        <a href="<?php echo $feature_link; ?>" class="button red"><?php echo $cta; ?></a>
                    </div>
                <?php } //endforeach; ?>
            <?php
            } // endif get_sub_field featured_book
        } //endwhile have_rows book_features;
    echo '</div>';
  } //endif