Perhaps you should try some spelling variations:
"open reresources software" » "open resources software", "open resource software", "open measures software", "open sources software", "open rereresources software"
"open source software" » "open resource software"

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: (("open source software") OR ("open reresources software")).
• Removing quotes may allow a broader search: (( open source software ) or ( open reresources software )).
• Adding a wildcard symbol may retrieve word variants: (("open source software") or ("open reresources software"))*.