Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hac duc » hoc duc, ha duc, thach duc
hanh di » hanh vi, hanh de, hang di
sach tu » sach thu, cach tu, sach uu
nang ma » sang ma, nang cao, mang may
duc van » duc va, duc tan, duc manh
tang ma » mang may, tang van
sach ty » sach y, sach thu, xach tay
hieu va » lieu va, hieu qua
di cua » dai cua, doi cua, de cua
va hac » van hac, va khac, va cac
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) OR (sach tu)) ((nang ma) OR (tang ma)) hoi. hieu va hac duc van hanh di cua tu~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ty) OR (sach tu)) ((nang ma) or (tang ma)) hoi. hieu va hac duc van hanh di cua tu~".
• Adding a wildcard symbol may retrieve word variants: te ((sach ty) OR (sach tu)) ((nang ma) or (tang ma)) hoi. hieu va hac duc van hanh di cua tu*.