Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach vu » sach va, sach tu, sach uu
hanh de » hanh ve
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
vu nang » vuc nang, va nang, vu dang
luc va » duc va, tuc va
va cam » va cham, va cac, va cao
loc va » hoc va

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach vu nang xa hoi. hieu va cam ((luc va) OR (loc va)) ((hanh de) or (hanh kem)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach vu nang xa hoi. hieu va cam ((luc va) OR (loc va)) ((hanh de) OR (hanh kem)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach vu nang xa hoi. hieu va cam ((luc va) OR (loc va)) ((hanh de) or (hanh kem)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach vu nang xa hoi. hieu va cam ((luc va) OR (loc va)) ((hanh de) or (hanh kem)) cua tre*.