Perhaps you should try some spelling variations:
su triet » su viet, ve triet
danh dai » danh dau, danh di, danh sai
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
su tien » su kien, su hien, tu tieng
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va
x hoi » xa hoi, o hoi, x ho

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 x hoi. ((hieu ve) or (hieu van)) am thuc va danh dai ((su triet) OR (su tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. ((hieu ve) OR (hieu van)) am thuc va danh dai ((su triet) OR (su tien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. ((hieu ve) or (hieu van)) am thuc va danh dai ((su triet) OR (su tien))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. ((hieu ve) or (hieu van)) am thuc va danh dai ((su triet) OR (su tien))*.