When searching for scholarly information online, it may be useful to limit your search by file type. Add filetype: or ext: to your search in order to do this.
archaeology civil war battlefield filetype:pdf
[PDF documents connected with the archaeology of Civil War battlefields]
chesapeake bay wildlife ext:xls
[spreadsheets in Excel format connected with the wildlife of the Chesapeake Bay]
Note: file searches may return items that require logins or access codes, or are otherwise inaccessible. If you find a journal article, for instance, that you can't access in full text, try VCU Libraries' journals or Interlibrary Loan.
One of the most effective ways to limit Google searches to useful results for research is to limit your search to particular websites or domains. Interested in finding only material originating from or related to academia? Search .edu domains. Only want to find information from government sources? Search .gov domains. Restricting to an individual site can be useful if you want to search a large website, or if you prefer to use the Google interface instead of the search box built into the site itself.
robot industrialization site:.edu
...finds information about robots and industrialization in academic domains.
richmond virginia site:cnn.com
...locates information from CNN about Richmond, and with the ease of Google searching.