Perhaps you should try some spelling variations:
yuan cheng » yuan chang, huang cheng, yu cheng
than china » han china, wuhan china, can china
tuan china » wuhan china, can china, taiwan china
yan wang » yuan wang, yang yang, qian wang
ren yang » ren yan, chen yang, dan yang
wong yue » wang yue, hong yu
yang dr » yang di, yang d, yang du
dr wong » dr ong, dr congo, dr kongo

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) or (yuan cheng)) ((than china) OR (tuan china)) ren yang dr wong yue ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((yan wang) OR (yuan cheng)) ((than china) OR (tuan china)) ren yang dr wong yue ;.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((yan wang) or (yuan cheng)) ((than china) OR (tuan china)) ren yang dr wong yue ;".
• Adding a wildcard symbol may retrieve word variants: ((yan wang) or (yuan cheng)) ((than china) OR (tuan china)) ren yang dr wong yue ;*.