Perhaps you should try some spelling variations:
"didactica de ricerca" » "didactique de ricerca", "didactic _ ricerca", "didactica di ricerca", "didactica e ricerca", "didactica de recerca"
"didactic a ricerca" » "didactic _ ricerca", "didactic atd ricerca", "didactica y ricerca", "didactic la ricerca", "didactic e ricerca", "didactic una ricerca"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("didactic a ricerca") OR ("didactica de ricerca")).
• Removing quotes may allow a broader search: (( didactic a ricerca ) or ( didactica de ricerca )).
• Adding a wildcard symbol may retrieve word variants: (("didactic a ricerca") or ("didactica de ricerca"))*.