Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
cua triet » cua viet, su triet, va triet
quoc ban » quoc bao, quoc quan, quoc binh
quoc lan » nuoc luan, quoc quan, quoc danh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cao hoi » cau hoi, cao hoc, tao hoi
hieu ve » hieu va, hieu van
tai cua » thai cua, tai cuc, tri cua
co hoi » co hoc, co loi
ve cam » ve cham, ve cac, va cam

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 ((cao hoi) or (co hoi)). hieu ve cam ((quoc ban) OR (quoc lan)) thanh tai cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((cao hoi) OR (co hoi)). hieu ve cam ((quoc ban) OR (quoc lan)) thanh tai cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((cao hoi) or (co hoi)). hieu ve cam ((quoc ban) OR (quoc lan)) thanh tai cua triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((cao hoi) or (co hoi)). hieu ve cam ((quoc ban) OR (quoc lan)) thanh tai cua triet*.