Perhaps you should try some spelling variations:
van nang » van quang, van dong, van dung
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
te sach » toc sach
cua tre » cua te, cua triet, dua tren
hanh le » thanh le, hanh ve, hanh de
dau luc » cau luc, dau luan, dau nuoc
luc van » luoc van, luu van, duc van
van dau » van dao, phan dau
cuu tre » cau tren, cau treo

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