Perhaps you should try some spelling variations:
yang yang » wang yang, wang yan
thanh van » thanh dam, thanh vu
yuan hui » yuan fei, jaan hui, tuan hua
chen yan » chen yang, chen tan, chen yun
thi tong » thi hong, thi mong, cho tong
tong hui » wang hui
yan thi » yan zhi, tran thi, dang thi

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "yang yang ((thanh van) OR (yuan hui)) chen yan thi tong hui ;~".
• Adding a wildcard symbol may retrieve word variants: yang yang ((thanh van) OR (yuan hui)) chen yan thi tong hui ;*.