Perhaps you should try some spelling variations:
vien thanh » viet thanh, tien thanh, dien thanh
trung sach » trung anh, trung svth
hiem ngan » kim ngan, viem gan
dung sach » duong sach, dung sai, dung cac
dung cong » dung trong
cong tinh » cong trinh, cong vinh, long tinh
toan tap » toan ban

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: hoc ((vien thanh) OR (hiem ngan)) - manh ((trung sach) OR (dung sach)) dung cong tinh toan tap~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((vien thanh) or (hiem ngan)) - manh ((trung sach) OR (dung sach)) dung cong tinh toan tap~".
• Adding a wildcard symbol may retrieve word variants: hoc ((vien thanh) or (hiem ngan)) - manh ((trung sach) OR (dung sach)) dung cong tinh toan tap*.