Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
danh sai » dung sai, danh bat, danh dau
danh vai » danh va, doanh van, dang van
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan, thuc day
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
o hai » co hai, so hai, o lai
o hoi » co hoi, o hoc, o hoa
ve am » va am

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 ve am thuc va ((danh vai) or (danh sai)) 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 ve am thuc va ((danh vai) OR (danh sai)) 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 ve am thuc va ((danh vai) or (danh sai)) cua triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) OR (o hai)). hieu ve am thuc va ((danh vai) or (danh sai)) cua triet*.