Documentation for sending hotel prices to Google.
Developer guide API reference XML reference
The Book on Google program allows Google partners in the travel industry to use a Google-hosted reservation and payment page.
Developer guide API Reference

Hotel Content

Documentation for sending hotel content information to Google, such as the Google Lodging Format.
Data Transfer Schema Protocol Buffer
Vacation Rentals allows Google partners in the travel industry to create reservation and payment pages for their individual Vacation Rental properties.
Developer guide