Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
hieu van » hieu va, thien van, lieu va
sang tao » hang tai
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
hieu ve » hieu va
sang ma » tang ma, nang ma, mang may
ca viet » va viet, co viet, hoa viet
vi ca » vit ca, li ca, va ca

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 ma) OR (sang tao)) hoi. ((hieu ve) or (hieu van)) am thuc va hanh vi ca viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach y ((sang ma) OR (sang tao)) hoi. ((hieu ve) OR (hieu van)) am thuc va hanh vi ca viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach y ((sang ma) OR (sang tao)) hoi. ((hieu ve) or (hieu van)) am thuc va hanh vi ca viet".
• Adding a wildcard symbol may retrieve word variants: hoc sach y ((sang ma) OR (sang tao)) hoi. ((hieu ve) or (hieu van)) am thuc va hanh vi ca viet*.