Perhaps you should try some spelling variations:
hanh vai » hanh vi, hanh va, hanh tai
hau thuc » huu thuc, ha thuc, mau thuc
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, te sach, tu cach
vai cua » dai cua, hai cua, lai cua
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
van hau » van ha, van hai, van dau
cua tre » cua te, cuu tre, cua triet
sang ma » tang ma, sang tao, mang may
nang ma » tang ma, nang cao, mang may
su sach » so sach, vu sach

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