Here, I've asked the database for images, maps, or physical objects about urban planning or advertising in the United States.
This broad search returns 68 different databases with primary sources. This is a great start, but still a lot to browse.
Here, I've restricted my previous search to databases with the word "industry" in their summary.
Keyword searching can help you uncover primary sources, just as in searching for scholarly articles. Knowing that you want to research the production of an object, in this case, will allow you to search this single database for historical advertisements of that object.