Perhaps you should try some spelling variations:
hieu suat » hieu luat, hieu qua
hieu sau » hieu su, tieu su, hieu va
sang lai » sang lap, mang lai, sang mai
van hanh » van thanh, ban hanh, van anh
sang tai » hang tai, sang tao, tang tai
san kyo » sang kyo, san khoa
vi cua » vai cua, di cua
xu van » tu van, vu van, su van
tu san » thu san, tu ban, tu can
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu san kyo ((sang lai) OR (sang tai)) hoi. ((hieu sau) or (hieu suat)) chao xu van hanh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu san kyo ((sang lai) OR (sang tai)) hoi. ((hieu sau) OR (hieu suat)) chao xu van hanh vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu san kyo ((sang lai) OR (sang tai)) hoi. ((hieu sau) or (hieu suat)) chao xu van hanh vi cua te".
• Adding a wildcard symbol may retrieve word variants: tu san kyo ((sang lai) OR (sang tai)) hoi. ((hieu sau) or (hieu suat)) chao xu van hanh vi cua te*.