Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
danh sai » dung sai, danh bat, danh dau
danh vai » danh va, doanh van, dang van
ve pham » vi pham, v pham, ve phan
hieu ve » hieu va, hieu van
sach tu » sach thu, cach tu, sach ty
tu nang » tru nang, tu nong, tu nano
cua te » cua tu
o hai » co hai, so hai, o lai

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 tu nang ((xa hoi) or (o hai)). hieu ve pham duc va ((danh vai) OR (danh sai)) cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach tu nang ((xa hoi) OR (o hai)). hieu ve pham duc va ((danh vai) OR (danh sai)) cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach tu nang ((xa hoi) or (o hai)). hieu ve pham duc va ((danh vai) OR (danh sai)) cua te".
• Adding a wildcard symbol may retrieve word variants: hoc sach tu nang ((xa hoi) or (o hai)). hieu ve pham duc va ((danh vai) OR (danh sai)) cua te*.