Perhaps you should try some spelling variations:
"differential psychology / http://id.loc.gov/authorities/subjects/sh85037923" » "differential psychology / https://id.loc.gov/authorities/subjects/sh85037923"
"difference psychology / http://id.loc.gov/authorities/subjects/sh85037923" » "difference psychology / https://id.loc.gov/authorities/subjects/sh85037923"

Try widening your search to All Fields.

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: "((\"differential psychology / http://id.loc.gov/authorities/subjects/sh85037923\") OR (\"difference psychology / http://id.loc.gov/authorities/subjects/sh85037923\"))".
• Removing quotes may allow a broader search: (( differential psychology / http://id.loc.gov/authorities/subjects/sh85037923 ) OR ( difference psychology / http://id.loc.gov/authorities/subjects/sh85037923 )).
• Adding a wildcard symbol may retrieve word variants: (("differential psychology / http://id.loc.gov/authorities/subjects/sh85037923") OR ("difference psychology / http://id.loc.gov/authorities/subjects/sh85037923"))*.