Perhaps you should try some spelling variations:
dem referat » zum referat
wang liang » wang yang
alan david » kaplan david, juan david, bulman david
liang dem » liang dan, liang wei
jan david » juan david, sahn david, john david
yan wang » yuan wang, yang yang, qian wang
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: yan wang liang dem referat ((jan david) or (alan david)) hong tan ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: yan wang liang dem referat ((jan david) OR (alan david)) hong tan ;*.