single book, search results

`"^https?://([^/]+\\.)?safaribooksonline\\.([a-zA-Z]{2,5}/"` Though, FYI, this doesn't cover TLDs, like co.uk. Looks like that's not going to be an issue for co.uk specifically right now, since the website doesn't yet exist, but it's "coming soon". There is no good list to match TLDs.