Go to Google's Advanced Search screen and try searchning for primary documents on the open web:
For the figure below, you may also try terms such as digital collection, digital archives, online collections, etc., in place of primary sources. Don't be afraid to experiment and try out different terms. Research takes time and patience. A lot of good primary sources can be found from the open web.
To narrow your results even further, have your search terms show up in the title of the web page: