Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
van thanh » ban thanh, van tuan
vien cac » vien bach, vien dai, vien da
van hanh » ban hanh, van anh, van ban
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cac luc » cau luc, coc luc, cac nuoc
cuc tre » duc tre, cua tre, cuu tre
mo hoc » mon hoc, co hoc
co loi » co hoi

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 ((mo hoc) or (co loi)). hieu vien cac luc ((van hanh) OR (van thanh)) tai cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((mo hoc) OR (co loi)). hieu vien cac luc ((van hanh) OR (van thanh)) tai cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((mo hoc) or (co loi)). hieu vien cac luc ((van hanh) OR (van thanh)) tai cuc tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((mo hoc) or (co loi)). hieu vien cac luc ((van hanh) OR (van thanh)) tai cuc tre*.