Perhaps you should try some spelling variations:
cau thuc » cau truc, cuu thuc, can thuc
hanh vai » hanh vi, hanh va, hanh tai
sach hay » sach han, sach ha, sach nay
lang hoa » hang hoa, lang ha, nang hoa
sach tay » xach tay, sach nay, sach tai
vai cua » dai cua, hai cua, lai cua
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
hieu ve » hieu van
hoa hoi » khoa hoi, hoa hoc, hoa doi

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

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sach tay) OR (sach hay)) lang hoa hoi. ((hieu ve) or (hieu va)) cau thuc va hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach tay) OR (sach hay)) lang hoa hoi. ((hieu ve) OR (hieu va)) cau thuc va hanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach tay) OR (sach hay)) lang hoa hoi. ((hieu ve) or (hieu va)) cau thuc va hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((sach tay) OR (sach hay)) lang hoa hoi. ((hieu ve) or (hieu va)) cau thuc va hanh vai cua tre*.