Perhaps you should try some spelling variations:
"resourcessssssssssssssssssssssssssss selection functions" » "resourcessssssssssssssssssssssssssss selection function" (Expand Search), "resourcesssssssssssssssssssssssssssss selection functions" (Expand Search)
"source detection functions" » "source detection function" (Expand Search), "sources detection functions" (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: (("resourcessssssssssssssssssssssssssss selection functions") OR ("source detection functions"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"resourcessssssssssssssssssssssssssss selection functions\") OR (\"source detection functions\"))*".
• Removing quotes may allow a broader search: (( resourcessssssssssssssssssssssssssss selection functions ) OR ( source detection functions ))*.