Perhaps you should try some spelling variations:
cua triet » cua viet, su triet
va triet » va thiet, va trien, ve triet
nam thuc » nam thuoc, am thuc, nam thu
hanh tai » thanh tai, hang tai, han tai
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
ky lang » ky nang, ky dang, ky tang
ha hoi » hoa hoi, ha noi, va hoi
ve nam » he nam, va nam, le nam

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 lang ((ha hoi) OR (xa hoi)). hieu ve nam thuc va hanh tai ((cua triet) or (va triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky lang ((ha hoi) OR (xa hoi)). hieu ve nam thuc va hanh tai ((cua triet) OR (va triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky lang ((ha hoi) OR (xa hoi)). hieu ve nam thuc va hanh tai ((cua triet) or (va triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky lang ((ha hoi) OR (xa hoi)). hieu ve nam thuc va hanh tai ((cua triet) or (va triet))*.