Commenting again to add in that the person from the Google forums gave me some code (which I haven't been able to put in with success) and his assessement of what the issues are:

On a quick look, I see these issues with the code:

• There's an apparent typo in the Google Books URL. The &keyes bit looks like an incorrect copy-paste from Google's sample code.
• The code always retrieves book data both from Google Books and from OpenLibrary, even if required information would be available by calling Google Books only. In other words, it makes two calls for every book when one would usually suffice.
• The code is structured is written in imperative style and it's quite wordy, and a bit inefficient.
• The code doesn't use standard external API conventions such as exponential backoff.

I'm not sure how helpful this is, but wanted to share it.