php で isbn解決

$request = "http://ecs.amazonaws.jp/onca/xml?".
"Service=AWSECommerceService".
"&Version=2011-08-01".
"&ResponseGroup=Small,Images".
"&Operation=ItemLookup".
"&ItemId=".$isbn;

こうだったのが

$request ="http://ecs.amazonaws.jp/onca/xml?Service=AWSECommerceService".
"&Version=2011-08-01".
"&AssociateTag=PutYourAssociateTagHere".
"&Operation=ItemLookup".
"&IdType=ISBN".
"&SearchIndex=Books".
"&ItemId=".$isbn;

こう

http://associates-amazon.s3.amazonaws.com/signed-requests/helper/index.html
がお役立ち