Perhaps you should try some spelling variations:
hieu cac » hieu luc, hieu va, hieu van
hien cac » thien cac, vien cac, dien cac
su triet » su viet, ve triet
hanh van » thanh van, khanh van, hanh va
va hanh » van hanh, va thanh, va danh
te sach » toc sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
su tien » su kien, su hien, tu tieng

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky nang xa hoi. thien ((hien cac) OR (hieu cac)) nuoc va hanh van ((su triet) or (su tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang xa hoi. thien ((hien cac) OR (hieu cac)) nuoc va hanh van ((su triet) OR (su tien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang xa hoi. thien ((hien cac) OR (hieu cac)) nuoc va hanh van ((su triet) or (su tien))".
• Adding a wildcard symbol may retrieve word variants: te sach ky nang xa hoi. thien ((hien cac) OR (hieu cac)) nuoc va hanh van ((su triet) or (su tien))*.