Perhaps you should try some spelling variations:
sach hoa » sach ha, sach hoi, bach hoa
toc hieu » toc thieu, hoc thieu, thuc hieu
doc hieu » toc thieu, hoc thieu, hoc hien
nghi cua » nghia cua, nghe cua, ngai cua
trung bo » truong bo, trung hoc, trung hoa
su sach » so sach, vu sach
hoc vi » hoc va, hoc viet

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su sach hoa ((toc hieu) OR (doc hieu)) nghi cua ets : ((trung bo) OR (nhung bai)) hoc vi đai~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach hoa ((toc hieu) OR (doc hieu)) nghi cua ets : ((trung bo) or (nhung bai)) hoc vi đai~".
• Adding a wildcard symbol may retrieve word variants: su sach hoa ((toc hieu) OR (doc hieu)) nghi cua ets : ((trung bo) or (nhung bai)) hoc vi đai*.