"The NTRS provides access to NASA's current and historical aerospace research and engineering results.
- NACA Collection: Citations and reports from the NACA Technical Report Server (TRS), 1915 to 1958.
- NASA Collection: Citations and documents created or sponsored by NASA, 1958 to present.
- NIX Collection: Citations and images, photos, movies and videos downloaded from the NASA Image eXchange and served out through NTRS." from web site
"Science.gov is a gateway to government science information and research results. Currently in its fifth generation, Science.gov provides a search of over 36 scientific databases and 200 million pages of science information with just one query, and is a gateway to 1,850+ scientific Websites.
The content for Science.gov is contributed by participating agencies committed to serving the information needs of the science-attentive citizen, including science professionals, students and teachers, and the business community." from web site