Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
va danh » va dinh, va dan, dia danh
va hanh » van hanh, va thanh, ban hanh
tang ma » tang van
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, sach thu
cac nop » cac hop, cac lop, cac nuoc
ve cac » va cac, vien cac
cua te » cua tu

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: tu sach ty ((mang may) OR (tang ma)) hoi. hieu ve cac nop ((va danh) OR (va hanh)) dai cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((mang may) or (tang ma)) hoi. hieu ve cac nop ((va danh) OR (va hanh)) dai cua te~".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((mang may) or (tang ma)) hoi. hieu ve cac nop ((va danh) OR (va hanh)) dai cua te*.