Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
dinh vai » dinh van, dinh vi, dinh va
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 dinh » van dinh, va kinh, va tinh
vai cua » dai cua, hai cua, lai 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 nano ((xa hoi) or (o hai)). hieu ve pham duc va dinh 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)). hieu ve pham duc va dinh vai cua te.
• Adding a wildcard symbol may retrieve word variants: hoc sach tu nano ((xa hoi) or (o hai)). hieu ve pham duc va dinh vai cua te*.