Perhaps you should try some spelling variations:
nhung cong » dung cong, hang cong, nhung don
thong cong » trong cong, tong cong, thong thong
hieu lang » chieu sang, hieu quang, nhieu tang
manh toan » thanh toan, anh tuan, tinh toan
hoc hieu » hoc thieu, hoc hien, doc hieu
toan ban » van ban
hanh va » hang va, hanh vi
han va » hang va, nhan va, ban 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 - hanh ((han va) or (hanh va)) ((nhung cong) OR (thong cong)) manh toan ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu lang - hanh ((han va) OR (hanh va)) ((nhung cong) OR (thong cong)) manh toan ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu lang - hanh ((han va) or (hanh va)) ((nhung cong) OR (thong cong)) manh toan ban".
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - hanh ((han va) or (hanh va)) ((nhung cong) OR (thong cong)) manh toan ban*.