Technical Reports (Grey Literature)
Virtual Technical Reports Center offers links to online providers of technical reports.
GreySource: A Selection of Web-based Resources in Grey Literature lists sources for grey literature (policy reports, technical reports) by general topics
For U.S. Government technical reports:
National Technical Reports Library offers full text technical reports.
TRAIL: Technical Report Archive and Image Library (1906-1992 (bulk 1920-1959)) includes reports published by numerous government agencies containing descriptions of research performed for U.S. government agencies largely prior to 1975. TRAIL searches the metadata of government technical reports. A selection of the reports is digitized and deposited for full text searching in HathiTrust and the University of North Texas Digital Library.
National Technical Information Service (1964- ) is a catalog of technical reports produced by Government agencies and their contractors. Overlaps with databases and indexes of the individual agencies. Online version continues U.S. Government research reports (1954-64; HathiTrust Version), Bibliography of technical reports (1949-54; HathiTrust Version), and Bibliography of scientific and industrial reports (1946-49; HathiTrust Version).
Science.gov searches a wide range of US government resources.
DTIC Online: Public Technical Reports searches Dept. of Defense technical reports and other resources.
Department of Energy (OSTI) reports
For the Environmental Protection Agency (EPA) use NSCEP/NEPIS - EPA's Gateway to Free Digital & Paper Publications
For the National Aeronautics and Space Administration (NASA) NASA Scientific and Technical Information and About NTRS: NASA Technical Reports Server (NTRS) offer overviews of, and links to, NASA information sources. NASA Technical Reports Server includes NASA (1958- ) and National Advisory Committee for Aeronautics (1916-1958) reports.
RePORT Expenditures and Results (RePORTER) query tool replaces CRISP (Computer Retrieval of Information on Scientific Projects) (1972- ) and is a searchable database of federally funded biomedical research projects.