Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » thien van, lieu va, hieu ve
tinh hai » tinh thai, tinh chat, trinh han
nang ma » sang ma, nang cao, mang may
tang ma » mang may, tang van
hieu va » lieu va, hieu qua
va tinh » may tinh
hai cua » thai cua, dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
du va » dau va, tu va, su va

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y ((nang ma) OR (tang ma)) hoi. ((hieu van) OR (hieu va)) cac du va tinh hai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y ((nang ma) OR (tang ma)) hoi. ((hieu van) or (hieu va)) cac du va tinh hai cua tre~".
• Adding a wildcard symbol may retrieve word variants: toc sach y ((nang ma) OR (tang ma)) hoi. ((hieu van) or (hieu va)) cac du va tinh hai cua tre*.