Perhaps you should try some spelling variations:
ban hanh » ban hang
van hanh » van thanh, van anh, van ban
te sach » toc sach
hac duc » hoc duc, ha duc, thach duc
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
nang ma » tang ma, nang cao, mang may
sang ma » tang ma, sang tao, mang may
va hac » van hac, va khac, va cac
di cua » dai cua, doi cua, de cua
cua tu » cua tuc, cua su, cua cu

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: te sach ty ((nang ma) OR (sang ma)) hoi. hieu va hac duc ((van hanh) OR (ban hanh)) di cua tu~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty ((nang ma) OR (sang ma)) hoi. hieu va hac duc ((van hanh) or (ban hanh)) di cua tu~".
• Adding a wildcard symbol may retrieve word variants: te sach ty ((nang ma) OR (sang ma)) hoi. hieu va hac duc ((van hanh) or (ban hanh)) di cua tu*.