Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
sach ky » sac ky, sach y, sach ty
cua tre » cuu tre, cua triet, dua tren
duc van » duc va, duc tan, duc manh
cac duc » cac du, cao duc, cac dac
qua cac » cua cac
su sach » so sach, vu sach
lang ha » long ha
lang xa » dang xay, lang van
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 ky ((lang xa) OR (lang ha)) 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 ky ((lang xa) OR (lang ha)) hoi. hieu qua cac duc van hanh vi ((cua tre) or (cua te))~".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((lang xa) OR (lang ha)) hoi. hieu qua cac duc van hanh vi ((cua tre) or (cua te))*.