Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
xang xa » mang xa, ang xa, dang xay
lang xa » lang ha, dang xay, lang van
qua cac » cua cac
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
cua tre » cuu tre, cua triet, dua tren
cua te » cua tu

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: su sach ty ((xang xa) OR (lang xa)) hoi. hieu qua cac duc van hanh vi ((cua tre) OR (cua te))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((xang xa) OR (lang xa)) hoi. hieu qua cac duc van hanh vi ((cua tre) or (cua te))~".
• Adding a wildcard symbol may retrieve word variants: su sach ty ((xang xa) OR (lang xa)) hoi. hieu qua cac duc van hanh vi ((cua tre) or (cua te))*.