Excellent Research Sources

I thought I'd put this list together of the places I use to research these old tools, just in case anyone wants to conduct similar research. 

Google Books - Excellent source for old magazine / publication articles, books, advertisements, etc.  (HINT: USE the search tools at the top of the page when searching for specific date ranges, etc.)

Worldcat - Searches hundreds, if not thousands of library archives for online editions, editions in their holdings, etc.

Patents from 1790 - 1836 - "The X-Series Patents"

Commissioner of Patents Reports - 1849 - 1864 - These contain every patent issued yearly.

Commissioner of Patents Reports - 1865 - 1920

Commissioner of Patents Reports - 1920 forward.

Google Patents - Perhaps even better than USPTO Patent Search

USPTO Patent Search - Good for newer patents, cumbersome and "iffy" for patents older than 1972

USPTO Patent Application Search - I'm putting this here for posterity, no good for older applications.

USPTO Trademark search (TSDR - Documents)

USPTO Trademark Search (TESS - Much less reliable but shows history of ownership)

Newspapers.com - This site adds thousands of pages of content every day and, while it is a pay site, it is an excellent resource for research.