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, ben david
jan david » juan david, sahn david, alan 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.

• Performing a fuzzy search may retrieve terms with similar spellings: wan wang liang wei referaten ((von david) OR (jan david)) ng tan ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "wan wang liang wei referaten ((von david) OR (jan david)) ng tan ;*".