Perhaps you should try some spelling variations:
hanh vai » hanh vi, hanh va, hanh tai
nang cau » nang cao, hang cau, nang dau
sach ky » sac ky, sach ty, sach kem
vai cua » dai cua, hai cua, lai cua
truc va » thuc va, thuc vat, trung va
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
va cao » va cac, va co, va dao
tuc va » thuc va, tuc xa, duc va

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

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