Perhaps you should try some spelling variations:
nhan vat » nhan tai, nhan dan, nhan tao
te sach » toc sach
hieu va » lieu va, hieu qua
cac tac » cac toc, cac bac, cac dac
nhan va » nhan tai, nhan dan, nhan tao
cua tre » cua te, cuu tre, cua triet
y nang » ly nang, v nang, may nang
tac va » tac da, tac xa, tuc va
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: te sach ((y nang) or (ky nang)) x hoi. hieu va cac tac va ((nhan vat) OR (nhan va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((y nang) OR (ky nang)) x hoi. hieu va cac tac va ((nhan vat) OR (nhan va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((y nang) or (ky nang)) x hoi. hieu va cac tac va ((nhan vat) OR (nhan va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ((y nang) or (ky nang)) x hoi. hieu va cac tac va ((nhan vat) OR (nhan va)) cua tre*.