Openly Available Sources Integrated Search (OASIS) is a search tool that aims to make the discovery of open content easier. OASIS currently searches open content from 115 different sources and contains 440,380 records.
The National Science Digital Library provides high quality online educational resources for teaching and learning, with current emphasis on the sciences, technology, engineering, and mathematics (STEM) disciplines
AMSER is a portal of educational resources and services built specifically for use by those in Community and Technical Colleges but free for anyone to use.