If you can't find what you are looking for, perhaps you are looking in the wrong place. Trying a different search tool will most likely get you different results. These are a few of your options:
Other bibliographic databases. Although the bibliographic databases have a big overlap, they all contain unique material. Try a different one to see if you find something new!
Google Scholar. If you are using a bibliographic database as your main search tool to find academic publications, you may want to use Google Scholar as a complement. Read more about how Google Scholar works under the tab Google Scholar.
Google. Depending on your subject, your information need will be different. Perhaps you need to find more non-academic publications, then Google may be the best option. Read more under the tab Google.