function apachesolr_solr_sort_form($form_id, $item_names, $items) {

  $form['solr-sort'] = array (
    '#type' => 'select',
    '#title' => t('Sortieren nach'),
    '#default_value' => 'sort_title',
    '#options' => $item_names,
    '#multiple' => FALSE,
  );
  $form['submit'] = array(
   '#type' => 'submit',
   '#value' => t('Suche')
  );
  $form['select_values'] = array (
    '#type' => 'value',
    '#value' => $items,
  );

  return $form;
}