Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
hien cac » thien cac, vien cac, hieu cac
su triet » su viet, ve triet
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
tinh ki » trinh ki, tinh vi, tinh kien
va tinh » may tinh
tu sach » thu sach, su sach, te sach
ty nang » ky nang, ty hang, ly nang
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: tu sach ((ty nang) or (ty xang)) x ho. hieu hien cac nuoc va tinh ki ((su triet) OR (su tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ty nang) OR (ty xang)) x ho. hieu hien cac nuoc va tinh ki ((su triet) OR (su tien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ty nang) or (ty xang)) x ho. hieu hien cac nuoc va tinh ki ((su triet) OR (su tien))".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty nang) or (ty xang)) x ho. hieu hien cac nuoc va tinh ki ((su triet) OR (su tien))*.