Third. In our library catalogue. It has links to the digital volume and also a box for full-text searching.
Our web application for logistical management produces a daily script for accessing GRIN, the Google partners management interface, obtains the item barcodes and adds an eight hundred and fifty six MARC label providing a link to the digital copy in Google Books.
Also it runs another script that uses a Google API to check whether there is a digital copy of a book in Google Books; if this is the case, the catalogue will show a search box for searching in this specific book fulltext.
Our catalog Cisne is available at http://cisne.sim.ucm.es/