Perhaps you should try some spelling variations:
hieu vien » hieu viec, thieu nien, hieu tieng
hieu hien » bieu hien, dieu hien, chieu chien
thu sach » tu sach, thuat sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
sach ky » sac ky, sach y, sach ty
va hanh » va thanh, va danh, ban hanh
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
cac lo » cac lop, cac co, cac bo
va cua » va chua, via cua, ca cua

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

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