Perhaps you should try some spelling variations:
dem referat » zum referat
yang liang » wang liang, yan liang, yang yang
wang yang » wang yan, wang liang, wang yanling
liang dem » liang dan, liang wei
von david » john david, ben david
jan david » juan david, sahn david, alan david
tan » than

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

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