Perhaps you should try some spelling variations:
cau triet » cau trieu, su triet, cua triet
van hanh » van thanh, ban hanh, van anh
hai cau » hai chau, hai chu, hai hau
va hanh » va thanh, va danh, ban hanh
cac tuc » cac toc, cac tu, cac tac
su sach » so sach, vu sach
qua cac » cua cac
y nang » ky nang, ly nang, v nang
o hai » co hai, so hai, o lai
o hoi » co hoi, o hoc, o hoa

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach y nang ((o hoi) or (o hai)). hieu qua cac tuc ((va hanh) OR (van hanh)) hai cau triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang ((o hoi) OR (o hai)). hieu qua cac tuc ((va hanh) OR (van hanh)) hai cau triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang ((o hoi) or (o hai)). hieu qua cac tuc ((va hanh) OR (van hanh)) hai cau triet".
• Adding a wildcard symbol may retrieve word variants: su sach y nang ((o hoi) or (o hai)). hieu qua cac tuc ((va hanh) OR (van hanh)) hai cau triet*.