Perhaps you should try some spelling variations:
"resourcessssssssssssssssssssssssssssss selection functions" » "resourcessssssssssssssssssssssssssssss selection function" (Expand Search), "resourcesssssssssssssssssssssssssssssss 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.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"resourcessssssssssssssssssssssssssssss selection functions\") OR (\"source detection functions\"))~".
• Removing quotes may allow a broader search: (( resourcessssssssssssssssssssssssssssss selection functions ) OR ( source detection functions ))~.
• Adding a wildcard symbol may retrieve word variants: (("resourcessssssssssssssssssssssssssssss selection functions") OR ("source detection functions"))*.