Perhaps you should try some spelling variations:
thuong cong » thong cong, thuong con, thuong dong
hieu quang » thieu quang, hieu quan, hieu qua
thanh tung » thanh cong
hieu lang » chieu sang, nhieu tang, hieu van
cong tan » cong tac, cong san, cong thanh
than cau » toan cau, than cap, thanh chau
phan cau » phan dau, phan cac, phan tu
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) OR (hieu quang)) - thanh tung va thuong cong tan ((than cau) or (phan cau))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu lang) OR (hieu quang)) - thanh tung va thuong cong tan ((than cau) OR (phan cau)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu lang) OR (hieu quang)) - thanh tung va thuong cong tan ((than cau) or (phan cau))".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu lang) OR (hieu quang)) - thanh tung va thuong cong tan ((than cau) or (phan cau))*.