private function source()
    {
        $source_url = 'https://www.iso.org/obp/ui/';

        file_get_contents($source_url);

        foreach ($http_response_header as $header) {
            if (substr($header, 0, 10) != 'Set-Cookie') {
                continue;
            }

            $cookie = explode(';', substr($header, 12))[0];
        }

        $resource_info = file_get_contents($source_url, false, stream_context_create([
            'http' => [
                'header' => "Content-type: application/x-www-form-urlencoded\r\nCookie: {$cookie}\r\n",
                'method' => 'POST',
                'content' => 'v-browserDetails=1&v-loc=https%3A%2F%2Fwww.iso.org%2Fobp%2Fui%2F%23search'
            ],
        ]));

        $csrf_token = json_decode(json_decode($resource_info)->uidl)->{'Vaadin-Security-Key'};

        $rpc_calls = [
            '"rpc":[["0","com.vaadin.shared.ui.ui.UIServerRpc","resize",["448","1370","1370","448"]],["62","com.vaadin.ui.JavaScript$JavaScriptCallbackRpc","call",["onCaptureSessionNotFound",[null]]]], "syncId":1',
            '"rpc":[["18","v","v",["selected",["S",["6"]]]]], "syncId":2',
            '"rpc":[["24","com.vaadin.shared.communication.FieldRpc$FocusAndBlurServerRpc","focus",[]]], "syncId":3',
            '"rpc":[["24","com.vaadin.shared.ui.button.ButtonServerRpc","click",[{"metaKey":false, "type":"1", "button":"LEFT", "relativeY":"19", "relativeX":"9", "clientX":"1079", "clientY":"309", "ctrlKey":false, "shiftKey":false, "altKey":false}]]], "syncId":4',
            '"rpc":[["85","com.vaadin.shared.ui.csslayout.CssLayoutServerRpc","layoutClick",[{"metaKey":false, "type":"8", "button":"LEFT", "relativeY":"14", "relativeX":"105", "clientX":"117", "clientY":"375", "ctrlKey":false, "shiftKey":false, "altKey":false},"86"]]], "syncId":5',
            '"rpc":[["53","v","v",["selected",["S",["16"]]]]], "syncId":6'
        ];

        $source_url = 'https://www.iso.org/obp/ui/UIDL/?v-uiId=0';

        foreach ($rpc_calls as $rpc_call) {
            $json = '{
                "csrfToken":"' . $csrf_token . '",
                ' . $rpc_call . '
            }';

            $result = file_get_contents($source_url, false, stream_context_create([
                'http' => [
                    'header' => "Content-type: application/json;charset=UTF-8\r\nCookie: {$cookie}\r\n",
                    'method' => 'POST',
                    'content' => $json,
                ],
            ]));
        }

        return $result;
    }