The Gateway to Oklahoma History (the above link), an Oklahoma Historical Society project, is the largest repository of Oklahoma newspapers online. The database covers hundreds of thousands of newspaper pages dating from the 1840s to the 1920s.
The below image shows the Basic Search screen. Basic search options are limited to searching the full text, metadata, title, subject or creator of a page:
To access the advanced searching feature, scroll down from the Basic Search page and click on the down caret of the "search" box and select the "Advanced Search" feature (you could also select "Guided Search" or "Proximity Search").
Below is an Advanced Search example looking for articles on Oklahoma in the Pauls Valley Democrat: Search for "Oklahoma" as the "Subject," then scroll down to the "Use Smart Filters" and select the Pauls Valley Democrat" from the "Collection" filter.
Below are the first two newspaper issues of the search results. Notice that the search results are for the Pauls Valley Sentinel, even though the search was for articles in the Pauls Valley Democrat. As can happen in the history of a newspaper, the Pauls Valley Sentinel, which ran from 1904-1906, was replaced by the Pauls Valley Democrat in September 1906:
Below is the initial display of the first page of the top article from Pauls Valley Sentinel, June 21, 1906:
Once you have "opened" a document, the "Magnify First Page" feature can be used to enlarge the newspaper page. This feature is on the left-hand side of the page halfway down.
General Tips for Using The Gateway to Oklahoma
The following video tutorial (below) provides detailed information on how to use the advanced search features, including searching by location and tips on viewing the search results: The Gateway to Oklahoma History video tutorial.