Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
danh sai » dung sai, danh bat, danh dau
dang van » hoang van, hang va
thuc day » thuc dan, thuc vat
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
ve am » va am
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 ve am thuc day ((dang van) 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 day ((dang van) 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 day ((dang van) or (danh sai)) cua triet*.