Technical reports may be difficult to find because there is no standard for their publication and distribution, and they are often not cataloged. However, each technical report has a number assigned by the National Technical Information Service, which is the most useful piece of information in making sure you find the right one.
The Engineering Library has some technical reports on microfiche. If you have the technical report number, you can check the microfiche cabinets to see if we have it.
Ellis Library also has some technical reports in government documents.