Perhaps you should try some spelling variations:
cau triet » cau trieu, su triet, cua triet
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
ky lang » ky dang, ky tang, tay lang
hieu va » lieu va, hieu qua
va hanh » va thanh, va danh, ban hanh
cac tu » cac thu, cach tu, cac du
vi cau » va cau, ve cau, di cau

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