Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
cua triet » cua viet, su triet, va triet
dinh vai » dinh van, dinh vi, dinh va
dua tren » dung tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
lo van » le van, vo van, so van
x hoi » xa hoi, o hoi, x ho
lo va » lao va, ly va, le va

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 ky nang x hoi. hieu vien bach ((lo va) OR (lo van)) dinh vai ((dua tren) or (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. hieu vien bach ((lo va) OR (lo van)) dinh vai ((dua tren) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. hieu vien bach ((lo va) OR (lo van)) dinh vai ((dua tren) or (cua triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. hieu vien bach ((lo va) OR (lo van)) dinh vai ((dua tren) or (cua triet))*.