Perhaps you should try some spelling variations:
vien dai » hien dai
su triet » su tien, ve triet
vien cac » vien bach, vien da, gian cac
tinh ki » trinh ki, tinh vi, tinh kien
va tinh » may tinh
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
su viet » so viet

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 x ho. hieu ((vien cac) or (vien dai)) nuoc va tinh ki ((su triet) OR (su viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang x ho. hieu ((vien cac) OR (vien dai)) nuoc va tinh ki ((su triet) OR (su viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang x ho. hieu ((vien cac) or (vien dai)) nuoc va tinh ki ((su triet) OR (su viet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang x ho. hieu ((vien cac) or (vien dai)) nuoc va tinh ki ((su triet) OR (su viet))*.