next-prev-page

  <?php if (!empty($post->post_parent)) {
                                $pagelist = get_pages("child_of=" . $post->post_parent . "&sort_column=menu_order&sort_order=asc&exclude=" . $post->ID);

                                $page_array = array();
                                foreach ($pagelist as $item) {
                                    $page_array[] += $item->ID;
                                }

                                if (!empty($page_array)) {

                                    if (count($page_array) >= 2) {
                                        $prevID = $page_array[0];
                                        $nextID = $page_array[1];
                                    } else {
                                        $prevID = $post->ID;
                                        $nextID = $page_array[0];
                                    }
                                }
                            ?>
                                <div class="navigation-pages">
                                    <a class="<?php if ($prevID == $post->ID) echo "disabled"; ?>" href="<?php echo get_permalink($prevID); ?>" title="<?php echo get_the_title($prevID); ?>">
                                        <?= get_the_title($prevID); ?></a>

                                    <a class="<?php if ($nextID == $post->ID) echo "disabled"; ?>" href="<?php echo get_permalink($nextID); ?>" title="<?php echo get_the_title($nextID); ?>"><?= get_the_title($nextID); ?></a>
                                </div>
                            <?php } ?>