public function retrieveSingle($id, $returnType = DOC_TYPE_SIMPLEXML) {
		$request = new CPS_RetrieveRequest($id);
		$this->_lastResponse = $this->_connection->sendRequest($request);
		foreach ($this->_lastResponse->getDocuments($returnType) as $document) {
			return $document;
		}
		return NULL;
	}