Perhaps you should try some spelling variations:
referaten von » referat vom, reformen von
reform von » form von
david hong » david ng
wang yang » wang yan, wang liang, wang yanling
wan wang » wen wang, yan wang, qian wang
yang wei » wang wei, fang wei, zhang wei
tan » than

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: wan wang yang wei ((((referaten von) OR (referat von))) OR (reform von)) david hong tan ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "wan wang yang wei ((((referaten von) OR (referat von))) or (reform von)) david hong tan ;~".
• Adding a wildcard symbol may retrieve word variants: wan wang yang wei ((((referaten von) OR (referat von))) or (reform von)) david hong tan ;*.