Perhaps you should try some spelling variations:
thanh do » thanh de, thanh pho, thanh hoa
thanh di » thanh doi, thanh de, thanh dinh
thi nang » thi cong, ki nang, thi hanh
hieu van » hieu va, thien van, lieu va
te sach » toc sach
cac luc » cau luc, coc luc, cac nuoc
van cac » van hac, van cau, van bac
ty hang » ly hang, ty xang, thi hang
cua tre » cua te, cuu tre, cua triet
luc va » duc va, tuc va, loc va
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 ((ty hang) or (thi nang)) x hoi. hieu van cac luc va ((thanh di) OR (thanh do)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((ty hang) OR (thi nang)) x hoi. hieu van cac luc va ((thanh di) OR (thanh do)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((ty hang) or (thi nang)) x hoi. hieu van cac luc va ((thanh di) OR (thanh do)) cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ((ty hang) or (thi nang)) x hoi. hieu van cac luc va ((thanh di) OR (thanh do)) cua tre*.