Most university and college libraries are also open to the public. You may, or may not, be allowed to check out books, but you certainly have the opportunity to look at their collection of books, magazines and journals and glean information from them while you are at the library. University libraries are often the repositories of technical journals and books that are not available through the public library system. If your invention is technical or has technical components, you may find the exact information you seek at your local university or college library.

Scattered across the country are approximately sixty Patent and Trademark Depository Libraries. Patent and Trademark Depository Libraries (PTDL’s) are housed within existing public, academic, state and research libraries. The librarians who work in the PTDL’s are specially trained by the United States Patent and Trademark Office and can help inventors perform patent and trademark searches using the printed Gazettes of issued patents as well as the latest computer programs and technology for patent and trademark searching. PTDL’s have all the listings for patents and trademarks that are found in the USPTO’s Virginia offices. There is no difference. This means that you can accomplish as thorough and complete a patent search at one of these PTDL’s as you can accomplish at the USPTO in Virginia.