Annual Reviews
Biological Abstracts
Encyclopedia of Earth
Encyclopedia of Life Sciences
MEDLINE

Oxford Reference Online
PubMed
State Academies of Science Abstracts
Web of Science

• Brenda - is a comprehensive enzyme information system.
• Entrze - is National Center for Biotechnology information (NCBI) 's life sciences search engine.

• Public Library of Science - is a freely available scientific and medical literature site made by scientists and physicians.
• Scirus - is the most comprehensive science search engine on the Internet. Scirus searches 450 million science-specific Web pages that contain scientific and scholarly data or articles on the Web.