Perhaps you should try some spelling variations:
"resourcesssssssssssssssssssssss selection function" » "resourcesssssssssssssssssssssss detection function" (Expand Search), "resourcessssssssssssssssssssssss selection function" (Expand Search)
"source selection functions" » "source detection functions" (Expand Search), "sources selection functions" (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: "((\"resourcesssssssssssssssssssssss selection function\") OR (\"source selection functions\"))~".
• Removing quotes may allow a broader search: (( resourcesssssssssssssssssssssss selection function ) OR ( source selection functions ))~.
• Adding a wildcard symbol may retrieve word variants: (("resourcesssssssssssssssssssssss selection function") OR ("source selection functions"))*.