Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
danh vai » danh sai, doanh van, dang van
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
danh va » doanh va, hanh va, anh va
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, nang ma
cac lo » cac lop, cac bo, cac ho
cac co » cac cong

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