Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
dua tren » dung tren
vien cac » vien bach, vien dai, vien da
dinh tri » chinh tri
lua tre » cua tre, luy tre, luat tri
xa dinh » xac dinh, va dinh, ba dinh
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
cac tac » cac toc, cac bac, cac dac
tac xa » tuc xa, tac da
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) or (su sach)) ky nang x hoi. hieu vien cac tac xa dinh tri ((lua tre) OR (dua tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky nang x hoi. hieu vien cac tac xa dinh tri ((lua tre) OR (dua tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky nang x hoi. hieu vien cac tac xa dinh tri ((lua tre) OR (dua tren))".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky nang x hoi. hieu vien cac tac xa dinh tri ((lua tre) OR (dua tren))*.