Perhaps you should try some spelling variations:
"documentary educational research" » "documenting education research", "documenting educational research", "documentary productional research", "elementary educational research"
"documentary education research" » "documenting education research", "documentary production research", "elementary 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: "((\"documentary educational research\") OR (\"documentary education research\"))".
• Removing quotes may allow a broader search: (( documentary educational research ) OR ( documentary education research )).
• Adding a wildcard symbol may retrieve word variants: (("documentary educational research") OR ("documentary education research"))*.