Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
danh vai » danh sai, danh va, doanh van
sach tu » sach thu, cach tu, sach ty
tu nano » truc nano
hieu ve » hieu va, hieu van
ve pham » vi pham, v pham, ve phan
va danh » va dinh, va dan, va hanh
vai cua » dai cua, hai cua, lai cua
cua te » cua tu
o hai » co hai, so hai, _ hai
o lai » o lao

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