Perhaps you should try some spelling variations:
"open resource software" » "open resources software" (Expand Search)
"open reresourcess software" » "open reresourcesss software" (Expand Search), "open resources software" (Expand Search), "open reresources software" (Expand Search)
"open resourcess software" » "open resourcesss software" (Expand Search), "open resources software" (Expand Search)

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: "((\"open resource software\") OR (((\"open reresourcess software\") OR (\"open resourcess software\"))))~".
• Removing quotes may allow a broader search: (( open resource software ) OR ((( open reresourcess software ) OR ( open resourcess software ))))~.
• Adding a wildcard symbol may retrieve word variants: (("open resource software") OR ((("open reresourcess software") OR ("open resourcess software"))))*.