Perhaps you should try some spelling variations:
ban hanh » ban hang
te sach » toc sach
sach ty » sach y, sach tu, sach thu
xang xa » lang xa, ang xa, dang xay
mang xa » lang xa, mang may, dang xay
hieu va » lieu va, hieu qua
va pham » van pham, va phat, va phap
duc ban » duc tan, duc van, dua ban
lai cua » hai cua, lai chau, thai cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ty ((xang xa) or (mang xa)) hoi. hieu va pham duc ban hanh ((lai cua) OR (dai cua)) thuoc~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty ((xang xa) OR (mang xa)) hoi. hieu va pham duc ban hanh ((lai cua) OR (dai cua)) thuoc.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty ((xang xa) or (mang xa)) hoi. hieu va pham duc ban hanh ((lai cua) OR (dai cua)) thuoc".
• Adding a wildcard symbol may retrieve word variants: te sach ty ((xang xa) or (mang xa)) hoi. hieu va pham duc ban hanh ((lai cua) OR (dai cua)) thuoc*.