Perhaps you should try some spelling variations:
"resourcesssssssssssssssssssssss selection functions" » "resourcesssssssssssssssssssssss detection functions" (Expand Search), "resourcessssssssssssssssssssssss 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.

• Performing a fuzzy search may retrieve terms with similar spellings: (("resourcesssssssssssssssssssssss selection functions") OR ("source selection function"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"resourcesssssssssssssssssssssss selection functions\") OR (\"source selection function\"))*".
• Removing quotes may allow a broader search: (( resourcesssssssssssssssssssssss selection functions ) OR ( source selection function ))*.