Perhaps you should try some spelling variations:
"resourcessssssssssssssssssss selection functions" » "resourcessssssssssssssssssss detection functions" (Expand Search), "resourcessssssssssssssssssss selection function" (Expand Search), "resourcesssssssssssssssssssss selection functions" (Expand Search)
"source selection functions" » "source detection functions" (Expand Search), "source selection function" (Expand Search), "sources selection functions" (Expand Search)

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