Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
dua tren » dung tren
so sach » so sanh, bo sach, co sach
sach ty » sach y, sach tu, sach thu
cuu tre » cua tre, cau tren, cau treo
dang ha » dong ha, dung ha, lang ha
ty dang » ty xang, ky dang, ty hang
xac va » tac va, ac va, bac va
ha hoi » hoa hoi, ha noi, xa hoi
tuc va » thuc va, truc va, tuc xa

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 ty dang ha hoi. hieu van nam ((xac va) or (tuc va)) hanh vi ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty dang ha hoi. hieu van nam ((xac va) OR (tuc va)) hanh vi ((dua tren) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: so sach ty dang ha hoi. hieu van nam ((xac va) or (tuc va)) hanh vi ((dua tren) or (cuu tre))*.