Perhaps you should try some spelling variations:
thanh cau » thanh chau, thanh mau, nhanh cau
hieu quan » hieu qua, lieu quan, thien quan
soc thiet » hoc thiet, so thiet, toc thieu
sach thi » sach thu, sach tai, sach tham
quan nam » quang nam, xuan nam, quan am
nam thuc » nam thuoc, am thuc, nam thu
thuc van » thuc vat, thuc dan, thuc va
van hanh » van thanh, ban hanh, van anh
hanh tai » thanh tai, hang tai, han tai
tai soc » tai so, tai hoc, thai son

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach thi) or (sach thieu)) thanh cau hoi. hieu quan nam thuc van hanh tai soc thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach thi) OR (sach thieu)) thanh cau hoi. hieu quan nam thuc van hanh tai soc thiet.
• Adding a wildcard symbol may retrieve word variants: tu ((sach thi) or (sach thieu)) thanh cau hoi. hieu quan nam thuc van hanh tai soc thiet*.