Perhaps you should try some spelling variations:
quan nhung » qua nhung, cua nhung, luan chung
nhung tung » nhung tuong, nhung dung, nhung vung
hieu quan » hieu qua, lieu quan, thien quan
hanh nang » anh nang, ganh nang, hanh mang
nang quan » ban quan, nang suat
hieu van » hieu va, thien van, lieu va
tung van » trung van, tang van, dung van
van than » van thanh, van thang, van tuan
than ban » thanh ban, toan ban, than man

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

• Performing a fuzzy search may retrieve terms with similar spellings: theo ((hieu quan) or (hieu van)) - hanh nang quan nhung tung van than ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo ((hieu quan) OR (hieu van)) - hanh nang quan nhung tung van than ban.
• Adding a wildcard symbol may retrieve word variants: theo ((hieu quan) or (hieu van)) - hanh nang quan nhung tung van than ban*.