Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
hieu vien » hieu viec, thieu nien, hieu tieng
danh vai » danh sai, danh va, doanh van
tu sach » thu sach, te sach, tu cach
vai cua » dai cua, hai cua, lai cua
va danh » va dinh, va dan, va hanh
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, nang ma
su sach » so sach, vu sach
cac lo » cac lop, cac co, cac bo
lo va » lo van, lao va, ly va

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

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