Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien bac » vien bach, vien cac, mien bac
danh sai » dung sai, danh bat, danh dau
danh vai » danh va, doanh van, dang van
tu sach » thu sach, su sach, te sach
bac cao » bao cao, bac can, bac cau
so sach » so sanh, bo sach, co sach
cua tre » cua te, cuu tre, cua triet
cao va » cao van, tao va, co va

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: ((tu sach) OR (so sach)) ky nang x ho. hieu vien bac cao va ((danh vai) OR (danh sai)) cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (so sach)) ky nang x ho. hieu vien bac cao va ((danh vai) OR (danh sai)) cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (so sach)) ky nang x ho. hieu vien bac cao va ((danh vai) OR (danh sai)) cua tre*.