Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien dai » hien dai
tinh hai » tinh thai, tinh chat, trinh han
dinh hai » dinh thai, dinh ha, dinh tai
te sach » toc sach
nang xa » nang x, lang xa, nang ma
cua tu » cua tuc, cua su, cua cu
bao va » bao ve, tao va, ban va
sach v » sach va, sach y, sach 2
lao va » tao va, cao va, dao va
v nang » va nang, vu nang, van nang

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te sach v nang xa hoi. hieu vien dai ((lao va) OR (bao va)) ((dinh hai) or (tinh hai)) cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach v nang xa hoi. hieu vien dai ((lao va) OR (bao va)) ((dinh hai) OR (tinh hai)) cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach v nang xa hoi. hieu vien dai ((lao va) OR (bao va)) ((dinh hai) or (tinh hai)) cua tu".
• Adding a wildcard symbol may retrieve word variants: te sach v nang xa hoi. hieu vien dai ((lao va) OR (bao va)) ((dinh hai) or (tinh hai)) cua tu*.