A technical report is a document that gives an account of the results or the progress of a research and/or development investigation. Where appropriate, it draws conclusions and makes recommendations, and is initially submitted to the person or organization for whom the work was carried out. Commonly, a technical report bears a number which identifies both the report and the issuing organization.
Technical Reports Websites
Many technical reports are available online for free.
National Technical Reports Library (NTRL) https://ntrl.ntis.gov/NTRL/
NTRL contains records for 3 million US federal technical reports dating back to 1964 and approximately 800,000 full-text reports, mainly from 1995 forward.
NASA Technical Reports Server (NTRS) https://ntrs.nasa.gov/search Includes current and historical aerospace literature (technical reports, journal articles, conference papers, images, photos, etc.) back to 1915.
Science.Gov http://www.science.gov/ The US government gateway to government sciencific information and research results.
Virtual Technical Reports Center / University of Maryland Libraries https://lib.guides.umd.edu/techreports A browseable site by institutions for technical reports, e-prints, reprints, dissertations, theses and research reports.