Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
truc van » thuc van, truc ban, truc dan
sach vay » sach va, sach hay, sach nay
truc va » thuc va, thuc vat, trung va
su viet » so viet
anh di » danh di, xanh di, anh d
x hoi » xa hoi, o hoi, x ho
di su » doi su, ki su, da su

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach vay) or (sach y)) nang x hoi. hieu vien cac ((truc van) OR (truc va)) anh di su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach vay) OR (sach y)) nang x hoi. hieu vien cac ((truc van) OR (truc va)) anh di su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach vay) or (sach y)) nang x hoi. hieu vien cac ((truc van) OR (truc va)) anh di su viet".
• Adding a wildcard symbol may retrieve word variants: su ((sach vay) or (sach y)) nang x hoi. hieu vien cac ((truc van) OR (truc va)) anh di su viet*.