Perhaps you should try some spelling variations:
thuong dong » phuong dong, tuong dong, chuong dong
thuong cong » thong cong, thuong con, truong cong
thanh tung » thanh cong
hieu lang » chieu sang, hieu quang, nhieu tang
hoc hieu » hoc thieu, hoc hien, doc hieu
than cau » phan cau, than cap, thanh chau
toan cau » toan cao, toan ban, toan tap
tung va » trung va, tuong va, dung va

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hieu lang - thanh tung va ((thuong cong) or (thuong dong)) ban ((than cau) OR (toan cau))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu lang - thanh tung va ((thuong cong) OR (thuong dong)) ban ((than cau) OR (toan cau)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu lang - thanh tung va ((thuong cong) or (thuong dong)) ban ((than cau) OR (toan cau))".
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - thanh tung va ((thuong cong) or (thuong dong)) ban ((than cau) OR (toan cau))*.