Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
van nang » van quang, van ban, van dong
doc sach » hoc sach, nuoc sach, dac sac
hieu va » lieu va, hieu qua
cao luc » bao luc, cao duc, cao suc
va lang » va nang, hoa lang
lang di » lang dai, hang di, lang du
cua tre » cua te, cuu tre, cua triet
v nang » va nang, vu nang, voi nang
va cao » va cac, va co, va dao
luc va » duc va, tuc va, loc va
di cua » dai cua, doi cua, de cua

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ((v nang) OR (van nang)) xa hoi. hieu va cao luc va lang di cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (doc sach)) ((v nang) OR (van nang)) xa hoi. hieu va cao luc va lang di cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) ((v nang) OR (van nang)) xa hoi. hieu va cao luc va lang di cua tre*.