Perhaps you should try some spelling variations:
va thanh » gia thanh, ban thanh, va tinh
te sach » toc sach
va hanh » van hanh, va danh, ban hanh
sach tu » sach thu, cach tu, sach ty
hieu va » lieu va, hieu qua
cu tren » tu tren, dua tren
mang xa » mang may, dang xay, mang cua
lang xa » lang ha, dang xay, lang van
cam tu » cam thu, nam tu, dam tu
va cam » va cham, va cac, va cao
di cu » di cau, di cua, di du

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 tu ((mang xa) or (lang xa)) hoi. hieu va cam tu ((va hanh) or (va thanh)) di cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach tu ((mang xa) OR (lang xa)) hoi. hieu va cam tu ((va hanh) OR (va thanh)) di cu tren.
• Adding a wildcard symbol may retrieve word variants: te sach tu ((mang xa) or (lang xa)) hoi. hieu va cam tu ((va hanh) or (va thanh)) di cu tren*.