Perhaps you should try some spelling variations:
nhung cong » dung cong, hang cong, nhung don
hanh trung » thanh trung, hanh trang, manh trung
thong cong » trong cong, tong cong, thong thong
hieu lang » chieu sang, hieu quang, nhieu tang
trung cua » truong cua, trung tuan, trung cap
hoc hieu » hoc thieu, hoc hien, doc hieu
toan cao » toan tap
toan ban » van ban

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 - hanh trung cua ((nhung cong) or (thong cong)) tac ((toan cao) OR (toan ban))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu lang - hanh trung cua ((nhung cong) OR (thong cong)) tac ((toan cao) OR (toan ban)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu lang - hanh trung cua ((nhung cong) or (thong cong)) tac ((toan cao) OR (toan ban))".
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - hanh trung cua ((nhung cong) or (thong cong)) tac ((toan cao) OR (toan ban))*.