Perhaps you should try some spelling variations:
thanh cau » thanh chau, thanh mau, nhanh cau
hanh thai » nhanh thai, hinh thai, hanh tai
son thiet » so thiet, soc thiet, toan thiet
sach thi » sach thu, sach tai, sach tham
nam thuc » nam thuoc, am thuc, nam thu
thuc van » thuc vat, thuc dan, thuc va
van hanh » van thanh, ban hanh, van anh
thai son » thai den, thai do, thai hoc
qua nam » quan nam, cua nam, quang nam

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 qua nam thuc van hanh thai son thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach thi) OR (sach thieu)) thanh cau hoi. hieu qua nam thuc van hanh thai son thiet.
• Adding a wildcard symbol may retrieve word variants: tu ((sach thi) or (sach thieu)) thanh cau hoi. hieu qua nam thuc van hanh thai son thiet*.