Perhaps you should try some spelling variations:
dem referat » zum referat
wang liang » wang yang
liang dem » liang dan, liang wei
von david » john david, ben david
jan david » juan david, sahn david, alan david
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: wen wang liang dem referat ((von david) OR (jan david)) ng tan ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "wen wang liang dem referat ((von david) OR (jan david)) ng tan ;*".