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

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((wan wang) or (wen wang)) liang wei referaten ((von david) OR (ben david)) ng tan ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((wan wang) OR (wen wang)) liang wei referaten ((von david) OR (ben david)) ng tan ;*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((wan wang) or (wen wang)) liang wei referaten ((von david) OR (ben david)) ng tan ;*".