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

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ky nang xa hoi. hieu van ha truc va doan vi ((dua tren) or (((cau treo) or (dau tren))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky nang xa hoi. hieu van ha truc va doan vi ((dua tren) OR (((cau treo) OR (dau tren)))).
• Adding a wildcard symbol may retrieve word variants: so sach ky nang xa hoi. hieu van ha truc va doan vi ((dua tren) or (((cau treo) or (dau tren))))*.