Perhaps you should try some spelling variations:
dau tieng » dau tien, cau tieng, day tieng
hanh vai » hanh vi, hanh va, hanh tai
van hanh » van thanh, ban hanh, van anh
vai dau » va dau, van dau, xvii dau
cam thu » cac thu, ca thu, cam phu
hieu ve » hieu va, hieu van
sang ma » tang ma, sang tao, mang may
nang ma » tang ma, nang cao, mang may
san ky » sang ky, van ky, dan ky
tu san » thu san, tu ban, tu can

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu san ky ((sang ma) or (nang ma)) hoi. hieu ve ((cam thu) OR (nam thu)) van hanh vai dau tieng~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu san ky ((sang ma) OR (nang ma)) hoi. hieu ve ((cam thu) OR (nam thu)) van hanh vai dau tieng.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu san ky ((sang ma) or (nang ma)) hoi. hieu ve ((cam thu) OR (nam thu)) van hanh vai dau tieng".
• Adding a wildcard symbol may retrieve word variants: tu san ky ((sang ma) or (nang ma)) hoi. hieu ve ((cam thu) OR (nam thu)) van hanh vai dau tieng*.