Perhaps you should try some spelling variations:
"research problems" » "research program", "research projects"
"research progress" » "research program", "research projects"
"research prozess" » "research process", "research propels", "research processes"

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (((("research prozess") OR ("research progress"))) OR ((("research problems") OR ("research project")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"research prozess\") or (\"research progress\"))) or (((\"research problems\") OR (\"research project\"))))".
• Removing quotes may allow a broader search: (((( research prozess ) or ( research progress ))) or ((( research problems ) OR ( research project )))).
• Adding a wildcard symbol may retrieve word variants: (((("research prozess") or ("research progress"))) or ((("research problems") OR ("research project"))))*.