PLOS non-profit organization dedicated to making scientific literature freely available by publishing a suite of influential open access journals across all areas of science and medicine. Collections relate to medicine and health, biology and life sciences, earth and environment, computer and information services, physics and chemistry, and research analysis and policy.

PubMed comprises more than 30 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 other publisher websites.

Functioning as a research and publishing network, ScienceOpen offers open access to more than 60 million articles from 25,000 journals in all areas of science. The advanced search function is highly detailed. Students need to register to view the full text of the articles, but registration is free.