Perhaps you should try some spelling variations:
wei referaten » den referaten, des referates
wang liang » wang yang
liang wei » xiang wei, zhang wei, wang wei
von david » john david, jan david
ben david » bevan david
wan wang » wen wang, yan wang, wang yang
ng tan » hong tan, wing tan

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

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