How To Search Across Multiple Sites Using Google Search?

Given this URL, I can do a site search across the site specified in the query string, on Google: https://www.google.com/search?q=something&sitesearch=subdomain1.site-abc.com T

Solution 1:

The OR is working well for me. Here an example example site:github.com OR site:gitlab.com OR site:bitbucket.org after:2018-01-01