Perhaps you should try some spelling variations:
dua tren » dung tren
hieu van » hieu va, thien van, lieu va
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
doan vi » doan va, don vi, doan thi
va doan » va doanh, van doan, va dan
truc va » thuc va, thuc vat, trung va
ha truc » ba truc, ha thuc, hang truc
cuu tre » cua tre, cau tren, cau treo
nang xa » lang xa, nang ma, mang xa
van ha » van hoa, van chat, van hanh

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: so sach ky ((nang xa) OR (nang x)) hoi. hieu van ha truc va doan vi ((dua tren) OR (cuu tre))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky ((nang xa) OR (nang x)) hoi. hieu van ha truc va doan vi ((dua tren) or (cuu tre))~".
• Adding a wildcard symbol may retrieve word variants: so sach ky ((nang xa) OR (nang x)) hoi. hieu van ha truc va doan vi ((dua tren) or (cuu tre))*.