Perhaps you should try some spelling variations:
referaten von » referat von, referat vom, reformen 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
form von » formen von
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 (((reform von) OR (form von)))) david hong tan ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "wan wang yang wei ((referaten von) or (((reform von) OR (form von)))) david hong tan ;~".
• Adding a wildcard symbol may retrieve word variants: wan wang yang wei ((referaten von) or (((reform von) OR (form von)))) david hong tan ;*.