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