Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
ban thanh » ban hanh, ban hang
va thanh » gia thanh, va tinh, le thanh
hieu van » hieu va, thien van, lieu va
sach ky » sac ky, sach y, sach ty
van cau » van dau, van hau, van chat
cau duc » cao duc, cau luc, chu duc
lam cua » nam cua, lam chat
tu sach » thu sach, su sach, te sach
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: tu sach ky nang ((o hoi) or (o hai)). hieu van cau duc ((va thanh) OR (ban thanh)) lam cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((o hoi) OR (o hai)). hieu van cau duc ((va thanh) OR (ban thanh)) lam cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((o hoi) or (o hai)). hieu van cau duc ((va thanh) OR (ban thanh)) lam cua triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) or (o hai)). hieu van cau duc ((va thanh) OR (ban thanh)) lam cua triet*.