Perhaps you should try some spelling variations:
va trien » va truyen, va thiet, va tuyen
hieu van » hieu va, thien van, lieu va
kinh tu » kinh te, tinh tu, dinh tu
te sach » toc sach
van lam » van nam
xuc va » duc va, tuc va, xac va
luc va » duc va, tuc va, loc va
o hoi » co hoi, o hoc, o hai

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 ((tu nano) or (truc nano)) o hoi. hieu van lam ((xuc va) OR (luc va)) kinh tu va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((tu nano) OR (truc nano)) o hoi. hieu van lam ((xuc va) OR (luc va)) kinh tu va trien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((tu nano) or (truc nano)) o hoi. hieu van lam ((xuc va) OR (luc va)) kinh tu va trien".
• Adding a wildcard symbol may retrieve word variants: te sach ((tu nano) or (truc nano)) o hoi. hieu van lam ((xuc va) OR (luc va)) kinh tu va trien*.