Perhaps you should try some spelling variations:
heilkunde 1991 » heilkunde 11, heilkunde 15.15, heilkunde 1
vier.ben.dt.gel.hno-heilkunde » view.ben.dt.gel.hno-heilkunde, vier.been.dt.gel.hno-heilkunde
verh.born.dt.gets.hno-heilkunde » very.born.dt.gets.hno-heilkunde, ver.born.dt.gets.hno-heilkunde, vers.born.dt.gets.hno-heilkunde, verh.born.dt.get.hno-heilkunde

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: (( vier.ben.dt.gel.hno-heilkunde 1991 ) OR ( verh.born.dt.gets.hno-heilkunde 1991 )).
• Adding a wildcard symbol may retrieve word variants: (( vier.ben.dt.gel.hno-heilkunde 1991 ) or ( verh.born.dt.gets.hno-heilkunde 1991 ))*.