Perhaps you should try some spelling variations:
vang hanh » van hanh, dang hanh, nang hanh
tac vang » cac van, tac dung, tac dong
te sach » toc sach
sach ty » sach y, sach tu, sach thu
ty mang » ty xang, ty hang, tin mang
may hoi » may thoi, tay hoi, mai hoi
qua cac » cua cac
cac tac » cac toc, cac bac, cac dac
hanh va » hang va, hanh vi
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 mang may hoi. hieu qua cac tac vang hanh va ((cua te) OR (cua tu))~.
• Adding a wildcard symbol may retrieve word variants: te sach ty mang may hoi. hieu qua cac tac vang hanh va ((cua te) or (cua tu))*.