When conducting historical research you will want to use a variety of primary and secondary sources.
Written about the time period you are studying
Include books, journal articles, reviews, websites
Look for words such as "history," "analysis," "context"
Narrow your results to scholarly (peer-reviewed) sources to find high-quality research-based articles
Written or created during the time you are studying
Include articles, newspaper articles, pictures, data, letters, etc.
When searching, do not use words such as "history" or "article." Instead, use a general key term, such as "education," and narrow down the dates to find what was being written about that topic during your time period
Try to use language from your time-period. Example: "vocational education"
Do not narrow your results to scholarly (peer-reviewed) sources
For all works:
Consider the slant or biases of the original author or historian writing about it