Perhaps you should try some spelling variations:
te sach » toc sach
hanh va » hang va
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
cac co » cac cong
co van » cao van, vo van, so van

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 ky ((nang xa) or (nang ma)) hoi. hieu va cac co van ((hanh vi) or (hanh va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky ((nang xa) OR (nang ma)) hoi. hieu va cac co van ((hanh vi) OR (hanh va)) cua tre.
• Adding a wildcard symbol may retrieve word variants: te sach ky ((nang xa) or (nang ma)) hoi. hieu va cac co van ((hanh vi) or (hanh va)) cua tre*.