public function getAddressBooks()
    {
        $website = $this->helper->getWebsite();
        $client = $this->helper->getWebsiteApiClient($website);

        $savedAddressBooks = $this->registry->registry('addressbooks');
        //get saved address books from registry
        if ($savedAddressBooks) {
            $addressBooks = $savedAddressBooks;
        } else {
            // api all address books
            $addressBooks = $client->getAddressBooks();
            $this->registry->unregister('addressbooks'); // additional measure
            $this->registry->register('addressbooks', $addressBooks);
        }

        return $addressBooks;
    }