YAZ extension you need for take (search) book (with possibility add "Book info" to self library) from YAZ servers.
Without YAZ - you will can continue search "book info" from Amazon.
We use PECL - YAZ extension from pecl.php.net/package/yaz.
If you use some host environment - from some provider - you must ask about extension install from Host support. Self you will can't install it. Host provider very seldom give so possibility.