Perhaps you should try some spelling variations:
huan thanh » thuan thanh, quan thanh, hoan thanh
han thanh » phan thanh, hoan thanh, nhan thanh
su sach » so sach
vu sach » vu bach, vu khach
hieu va » lieu va, hieu qua
bac dai » bach mai
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
va bac » van bac, va cac, va bai
x hoi » xa hoi, o hoi, x ho

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) or (vu sach)) y nang x hoi. hieu va bac dai ((han thanh) OR (huan thanh)) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) y nang x hoi. hieu va bac dai ((han thanh) OR (huan thanh)) dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (vu sach)) y nang x hoi. hieu va bac dai ((han thanh) OR (huan thanh)) dai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu sach)) y nang x hoi. hieu va bac dai ((han thanh) OR (huan thanh)) dai cua tre*.