Google Scholar was created as a tool to congregate scholarly literature on the web. From one place, students have the ability to hunt for peer-reviewed papers, theses, books, abstracts and articles from academic publishers, professional societies, preprint repositories, universities and other scholarly organizations
Google Books allows web users to browse an index of thousands of books, from popular titles to old, to find pages that include your search terms. Once you find the book you are looking for, you can look through pages, find online reviews and learn where you can get a hard copy
Operated by the company that brings you Word, PowerPoint and Excel, Microsoft Academic is a reliable, comprehensive research tool. The search engine pulls content from over 120 million publications, including scientific papers, conferences and journals. You can search directly by topic, or you can search by an extensive list of fields of study. For example, if you're interested in computer science, you can filter through topics such as artificial intelligence, computer security, data science, programming languages and more.
A self-described "computational knowledge engine," Wolfram Alpha does not so much provide search results as it does search answers. Simply type in a topic or question you may be interested in, such as, "What is the function of the pancreas?" and the answer will show up without making you scroll through pages of results. This is especially handy for those in need of math help
ResearchGate is a unique social networking site for scientists and researchers. Over 11 million researchers submit their work, which totals more than 100 million publications, on the site for anyone to access. You can search by publication, data and author, or you can even ask the researchers questions. Though it's not a search engine that pulls from external sources, ResearchGate's own collection of publications provides a hearty selection for any inquisitive scholar
Scopus is the largest abstract and citation database of peer-reviewed literature: scientific journals, books and conference proceedings. Delivering a comprehensive overview of the world's research output in the fields of science, technology, medicine, social sciences, and arts and humanities, Scopus features smart tools to track, analyze and visualize research