Perhaps you should try some spelling variations:
"berg wilhelm friedrich hegel" » "berger wilhelm friedrich hegel", "georg wilhelm friedrich hegel", "bei wilhelm friedrich hegel"
"werk wilhelm friedrich engels" » "werner wilhelm friedrich engels", "bei wilhelm friedrich engels", "junk wilhelm friedrich engels"

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: (("berg wilhelm friedrich hegel") OR ("werk wilhelm friedrich engels")).
• Removing quotes may allow a broader search: (( berg wilhelm friedrich hegel ) or ( werk wilhelm friedrich engels )).
• Adding a wildcard symbol may retrieve word variants: (("berg wilhelm friedrich hegel") or ("werk wilhelm friedrich engels"))*.