Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
sang mai » sang ma, sang tai, lang mai
cua viet » ca viet, hoa viet, cua vat
mai hoi » mai khoi, dai hoi, lai hoi
hieu ve » hieu va, hieu van
y sang » _ sang, duy sang
ve cau » ke cau, va cau, ve cac
loc va » hoc va, luc va
vi cua » vai cua, di cua

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 y sang mai hoi. hieu ve cau ((duc va) or (loc va)) hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach y sang mai hoi. hieu ve cau ((duc va) OR (loc va)) hanh vi cua viet.
• Adding a wildcard symbol may retrieve word variants: hoc sach y sang mai hoi. hieu ve cau ((duc va) or (loc va)) hanh vi cua viet*.