Perhaps you should try some spelling variations:
su triet » su viet, ve triet
van hanh » van thanh, ban hanh, van anh
cham luu » cham cuu, chat lua, phap luu
tu sach » thu sach, su sach, te sach
sach ly » sach y, sach lo, sach ty
luu van » cuu van, luan van, luu hanh
vu cham » va cham, vu kham, tu cham
hieu vu » hieu va, hieu ve, hieu su
lang xa » lang ha, dang xay, lang van
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 ly ((lang xa) or (nang x)) hoi. hieu vu cham luu van hanh vi ((su triet) OR (su tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ly ((lang xa) OR (nang x)) hoi. hieu vu cham luu van hanh vi ((su triet) OR (su tien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ly ((lang xa) or (nang x)) hoi. hieu vu cham luu van hanh vi ((su triet) OR (su tien))".
• Adding a wildcard symbol may retrieve word variants: tu sach ly ((lang xa) or (nang x)) hoi. hieu vu cham luu van hanh vi ((su triet) OR (su tien))*.