(Mostly for computer science)
Today most of the academic search is done on Google Scholar. At least that’s what I do and also hear from colleagues that they do. However, using only one academic search engine may narrow down our search results. I decided to build this list after a coffee break with colleagues where we have discussed the strange search behavior of Google Scholar that we sometimes encounter. As you can see at the very bottom of the page, I have used a Wikipedia article to find out some of these search engines. The list on Wikipedia is longer and more extensive. Here in my list, I include only the ones that I found useful to discover new research papers.
As a small experiment, I ran the same search keywords in all of these search engines, and I was surprised to see how different the results were. Some of these engines have really extensive filtering properties. Some of them index only the open access research papers, or maybe fewer publishers. I haven’t run a qualitative study, so I can’t say which one is better. However, I think the more search engines we use in our research the better it is.
If you know other useful search engines please let me know, I’m happy to extend this list.
Scopus by Elsevier
Web of Science
World Wide Science