Google Scholar (https://scholar.google.com) is a Google search engine that indexes scholarly sources, such as articles, books, theses, abstracts, and court opinions from academic publishers, professional societies, online repositories, universities, and other websites. It is a powerful tool used by many researchers, though it doesn't always provide full-text access to materials.
Make the most of Google Scholar:
ResearchGate (https://www.researchgate.net/) is a social networking and resource-sharing site for scientists and scholars. You can contact an author via ResearchGate and ask for a copy of an article.
Connected Papers (https://www.connectedpapers.com/) is a visual tool to help researchers find academic papers that are related by content. Search for a paper, and this tool creates a graph of papers that are positioned based on similarity, not citations.