I'm a webmaster and I have a question about how google or other search engines index site that are search engines. In a normal site, from the homepage if I created a link to all the section and pages of my websites, google index all the pages of my sites.
But sometimes I see sites that they don't have this link to internal pages, for example:
search "waitress london" in google, you find this result:
But if you go on the site homepage
you have only a search form like google, there is no link to internal search, and I can't find external site linkink to
So my question is:
How google know this link?