Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
danh hai » dang hai, lanh hai, manh hai
sach tu » sach thu, cach tu, sach ty
tu nang » tru nang, tu nong, tu nano
hieu ve » hieu va, hieu van
ve pham » vi pham, v pham, ve phan
va danh » va dinh, va dan, va hanh
hai cua » thai cua, dai cua, hoi cua
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 hai 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 hai 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 hai cua te*.