Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh vai » hanh vi, hanh va, hanh tai
van cau » van dau, van hau, van chat
vai cua » dai cua, hai cua, lai cua
chuc va » thuc va, thuc vat
phuc va » phuc vu, thuc va, thuc vat
tu sach » thu sach, su sach, te sach
sach ly » sach y, sach lo, sach ty
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
cua tre » cua te, cuu tre, cua triet

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 ly ((nang xa) or (nang ma)) hoi. hieu van cau ((phuc va) OR (chuc va)) hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ly ((nang xa) OR (nang ma)) hoi. hieu van cau ((phuc va) OR (chuc va)) hanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ly ((nang xa) or (nang ma)) hoi. hieu van cau ((phuc va) OR (chuc va)) hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ly ((nang xa) or (nang ma)) hoi. hieu van cau ((phuc va) OR (chuc va)) hanh vai cua tre*.