Perhaps you should try some spelling variations:
va thanh » gia thanh, ban thanh, le thanh
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
va tinh » may tinh
vai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet
nam tu » nam thu, nam thuc

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