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Hm, looks like Alta-Vista is still around...

The results come via a rebranded Yahoo! search, which itself consists of rebranded Bing results.

I believe DDG uses a variety of sources for results, including but not limited to Bing.

I'd add https://ixquick.com to the list.

Also, using a search engine directly is not the same thing as using it through one of these intermediaries (especially while logged in).