Perhaps you should try some spelling variations:
cau thuc » cau truc, cuu thuc, can thuc
thuc day » thuc dan, thuc vat
day hanh » day nhanh, day thanh, dao hanh
hanh vai » hanh vi, hanh va, hanh tai
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
vai cua » dai cua, hai cua, lai cua
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 sach y ((mang may) or (nang cao)) hoi. ((hieu ve) or (hieu qua)) cau thuc day hanh vai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((mang may) OR (nang cao)) hoi. ((hieu ve) OR (hieu qua)) cau thuc day hanh vai cua te.
• Adding a wildcard symbol may retrieve word variants: tu sach y ((mang may) or (nang cao)) hoi. ((hieu ve) or (hieu qua)) cau thuc day hanh vai cua te*.