Perhaps you should try some spelling variations:
thanh de » hanh de, thanh ve, thanh do
te sach » toc sach
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
vu nang » vuc nang, va nang, vu dang
luc va » duc va, tuc va, loc va
v nang » va nang, van nang, voi nang
de cua » le cua, te cua, dieu cua
va cam » va cham, va cac, va cao
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 ((v nang) OR (vu nang)) x hoi. hieu va cam ((luc va) or (thuc vat)) thanh de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((v nang) OR (vu nang)) x hoi. hieu va cam ((luc va) OR (thuc vat)) thanh de cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((v nang) OR (vu nang)) x hoi. hieu va cam ((luc va) or (thuc vat)) thanh de cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ((v nang) OR (vu nang)) x hoi. hieu va cam ((luc va) or (thuc vat)) thanh de cua tre*.