Photo: elian / Wikimedia Commons / CC BY 2.5
Top search engines for research include Google and Bing. That answer is plain, but the useful part is in the difference between them. Google remains the largest general web search engine, and Bing is also a major general search engine with its own ranking system and research tools.
When I look at this kind of question, I start with coverage. A general search engine is broad, but it is not complete. It crawls the open web, then ranks pages by its own method. That means the same query can surface different results in Google and Bing, even when both are searching the same topic.
For research, that difference matters. Google is often the first place people check because it is so widely used and deeply indexed. Bing is not a small side option. Microsoft presents it as a search engine built to help users find authoritative web pages and to support research-style use. In practice, that gives researchers two large indexes to compare when a topic is messy, new, or unevenly covered.
I treat this as a simple search habit, not a grand theory. One engine can miss a page. Another may surface it. That is useful when a search needs breadth, or when a topic is shaped by different page titles, phrases, or site structures.
There is one limit that stays important. Neither Google nor Bing is a full record of the web. Neither shows everything that exists, and neither explains every ranking choice in full detail. Search results also change over time, so a list of top engines is always a moving target. A researcher can trust the scale of these engines, but not assume their results are final.
That is the main point behind the headline. Top search engines for research include Google and Bing, but the real lesson is narrower: each one has broad reach, each one has limits, and each one may find different material first. For a reader of The Source List, that is the kind of plain fact that matters most, because the useful source is the one whose coverage and limits are stated clearly.