Databases, preprint servers, and reference managers for running a literature review without losing a single source. One link for the whole lab.
Google Scholar provides a simple way to broadly search for scholarly literature. Search across a wide variety of disciplines and sources: articles, theses, books, abstracts and court opinions.

PubMed® comprises more than 40 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full text content from PubMed Central and publisher web sites.
Preprints in physics, maths, CS, and quantitative fields.
Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.

Connected Papers is a visual tool to help researchers and applied scientists find academic papers relevant to their field of work.

Semantic Scholar uses groundbreaking AI and engineering to understand the semantics of scientific literature to help Scholars discover relevant research.
JSTOR is a digital library of academic journals, books, and primary sources.