Perhaps you should try some spelling variations:
hieu vien » hieu viec, thieu nien, hieu tieng
hieu hien » bieu hien, dieu hien, chieu chien
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
cac dac » cac dan, cac dai, cac bac
va hanh » van hanh, va thanh, va danh
cua tre » cuu tre, cua triet, dua tren
dac va » duc va, day va, dat va
cua te » cua tu
x hoi » xa hoi, o hoi, x ho

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky nang x hoi. ((hieu vien) or (hieu hien)) cac dac va hanh vi ((cua tre) OR (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang x hoi. ((hieu vien) OR (hieu hien)) cac dac va hanh vi ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang x hoi. ((hieu vien) or (hieu hien)) cac dac va hanh vi ((cua tre) OR (cua te))".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang x hoi. ((hieu vien) or (hieu hien)) cac dac va hanh vi ((cua tre) OR (cua te))*.