How to see how many times a document has been cited? I'm working on my thesis and I'd like to see if some documents that I'll use have been used before to see if the topic and focus I'm working on has been done before. At the moment it seems it hasn't, I looked for citations in Google scholar and it has only 1 citation, Academia.edu has around 2000, but I must have Academia Premium to see it. Is there any other way to look for citations? Is it worth to have Academia Premium?
I used a lot Web of Science. You can see who cited what (if it is indexed) and it usually has links to the full text. See its wiki page for more information, including links to other search engines.

Where I work, the administrative staff takes their bibliometrics from Web of Science.