Perhaps you should try some spelling variations:
quan nhung » qua nhung, cua nhung, luan chung
nhung vung » nhung dung, nhung huong, nhung tuong
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
vung dan » vung dat, dung dan, tung dan
dan than » dan chan, ban than, van than
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 vung dan 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 vung dan than ban.
• Adding a wildcard symbol may retrieve word variants: theo ((hieu quan) or (hieu van)) - hanh nang quan nhung vung dan than ban*.