Perhaps you should try some spelling variations:
"continuum source in educational research" » "continuous sources in educational research", "continuum scale in educational research"
"continuum source in education research" » "continuous sources in education research", "continuum scale in education research"

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"continuum source in educational research\") OR (\"continuum source in education research\"))".
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