Perhaps you should try some spelling variations:
dieu hien » dieu khien, dieu kien, bieu hien
su triet » su viet, su tien, ve triet
hien cac » thien cac, vien cac, hieu cac
dinh vai » dinh van, dinh vi, dinh va
cua tre » cua te, cuu tre, cua triet
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang
bao va » bao ve, tao va, ban va
lao va » tao va, cao va, dao 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 ty nang xa hoi. dieu hien cac ((lao va) OR (bao va)) dinh vai ((cua tre) or (su triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang xa hoi. dieu hien cac ((lao va) OR (bao va)) dinh vai ((cua tre) OR (su triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang xa hoi. dieu hien cac ((lao va) OR (bao va)) dinh vai ((cua tre) or (su triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang xa hoi. dieu hien cac ((lao va) OR (bao va)) dinh vai ((cua tre) or (su triet))*.