Perhaps you should try some spelling variations:
hieu quan » hieu qua, lieu quan, thien quan
nang cong » nang song, dang cong, bang cong
tang van » dang van, hoang van, trong van
dan toan » van toan, manh toan, xuan toan
dan than » dan chan, ban than, van than
ho hieu » ho chieu, hoi hieu, nho hieu
tang va » trang va, thang va, tang vat

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

• Performing a fuzzy search may retrieve terms with similar spellings: ho hieu quan - hanh ((tang va) or (tang van)) nang cong ((dan toan) OR (dan than)) cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu quan - hanh ((tang va) OR (tang van)) nang cong ((dan toan) OR (dan than)) cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho hieu quan - hanh ((tang va) or (tang van)) nang cong ((dan toan) OR (dan than)) cao".
• Adding a wildcard symbol may retrieve word variants: ho hieu quan - hanh ((tang va) or (tang van)) nang cong ((dan toan) OR (dan than)) cao*.