allowed values for node/entity/user reference field Can you get allowed values for reference field?

i tried with:

$all_fields_info = field_info_fields();
$allowed_values= list_allowed_values($all_fields_info["field_user_ref"]);


but it is not working ..
For an entityreference fields use:

$allowed_values = entityreference_get_selection_handler("field_user_ref")-&gt;getReferencableEntities();