Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
xang hai » hang hai, dang hai, bang hai
dua tren » dung tren
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
tinh lai » tinh lao, tinh hai, minh lai
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
hai hoi » dai hoi, hai moi, hai hai
luc va » duc va, tuc va, loc va
xuc va » duc va, tuc va, xac va

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ty xang hai hoi. hieu van cham ((xuc va) or (luc va)) tinh lai ((dua tren) or (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ty xang hai hoi. hieu van cham ((xuc va) OR (luc va)) tinh lai ((dua tren) OR (cua tre)).
• Adding a wildcard symbol may retrieve word variants: hoc sach ty xang hai hoi. hieu van cham ((xuc va) or (luc va)) tinh lai ((dua tren) or (cua tre))*.