A great way to find sources is to use the existing web of citations between academic sources, called backward and forward citing.
Backward citation means looking at the references page of a book or article and visiting the articles your source cites that are relevant to your topic. This is a great way of getting a handle on the scholarship surrounding a topic.
Forward citation means finding sources that cite the article you're currently reading. Google Scholar has an excellent tool to do this: just copy and paste the title into the search bar, then select the "cited by" link beneath the result. This will generate the articles that have cited this article in their references page.
A handy but underused way of quickly scanning an article (or a website or another kind of file) is the "Find" function. "Control+F" (or "Command+F" on a Mac) is the keyboard shortcut for the Find command. If you're in a document or in a web browser, pressing the Ctrl key + the F key will bring up a search box in the top right corner of the screen. You can then type in a keyword or phrase to find places where that word or phrase is used in the text, often helpful for locating relevant sections.