Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
su triet » su viet, su tien, ve triet
trinh ki » trinh khi, trinh ky, trinh di
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
vien cac » vien bach, vien dai, vien da
thu sach » thuat sach, thuoc sach, thu hoach
ty nang » ky nang, ty xang, ty hang
tinh ki » tinh vi, tinh kien, trinh khi
tu sach » su sach, te sach, tu cach

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