Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
thanh lam » thanh lap, hanh lam, thanh nam
hieu van » hieu va, thien van, lieu va
lam cua » nam cua, lam chat
hau duc » huu duc, pham duc, phan duc
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
ha duc » ho duc, ha dac, xa duc
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 ((hau duc) or (ha duc)) gia 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 ((hau duc) OR (ha duc)) gia 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 ((hau duc) or (ha duc)) gia thanh lam cua triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) OR (o hai)). hieu van ((hau duc) or (ha duc)) gia thanh lam cua triet*.