如何从Array for DHRU保存分离的API结果？

Im using a API script from DHRUfusion. Im using this code:

$api = new DhruFusion();
$para['IMEI'] = "013405000408134";
$para['ID'] = "581";
$request = $api->action('placeimeiorder', $para);

/** CODE BELOW WILL OUTPUT RESULTS **/

echo '<PRE>';
print_r($request);
echo '</PRE>';

As you see ARRAY $request will print this Array:

 Array
(
    [ID] => 581
    [IMEI] => 013405000408134
    [SUCCESS] => Array
        (
            [0] => Array
                (
                    [MESSAGE] => Order received
                    [REFERENCEID] => 1033747
                )

        )

    [apiversion] => 2.0.0
)

Now I want to save "1033747" (REFERENCEID) as $REFID.

My question is: How can I point REFERENCEID to REFID? I need all results separated as shown below.

Is this method below correct way to do that? :

<?php 
$REFID = "$request[REFERENCEID]" ;
$IMEI = "$request[IMEI]" ;
?>

Try this:

$IMEI = $request["IMEI"];
$REFID = $request["SUCCESS"][0]["REFERENCEID"];