Although Google is an amazing tool, just typing something into its search bar doesn't always give you what you need. Search engines often yield webpages that are only related to a few of the terms you're looking for, from the wrong website, too old to use, or not in a useable format.
That's why you should check out Google Advanced Search, a free tool for making Internet research easier. It basically looks like an online form, and you can access it at www.google.com/advanced_search.
With the form's first few fields, you can improve your search results by putting tight controls on your search terms. Here, you can tell Google to find pages with all words, with a specific phrase, with any of your keywords, without certain keywords, or with specific ranges of numbers. You might use these tools to find pages that mention Clark Kent but not Superman.
The next group of fields lets you narrow your search results with different filters. Here, you can limit your search results to pages that are in a particular language, from a certain region of the world, on a specific website or domain, from a distinct period of time, or in an explicit file format (such as PDF). With these tools, you might narrow your Clark Kent search to only include PDF documents published on Forbes.com between 2012 and 2013, or to Spanish-language websites from the United States.