Perhaps you should try some spelling variations:
wei referaten » den referaten, des referates
yan xiang » yan liang, lian xiang, yang liang
xiang wei » liang wei, zhang wei, wang wei
von david » john david, ben david
jan david » juan david, sahn david, alan david
hong ghi » zhong zhi, hong g, hong hai
wan yan » wang yan, nan yan, wai yan

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

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