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