Perhaps you should try some spelling variations:
chiet tach » chieu sach
hien tach » thien hach, vien bach, hien hanh
tranh cua » doanh cua, manh cua
tong cong » trong cong, cong cong, dang cong
dung cong » dung trong
phap toan » phap hoan, phap luan, phap phan
toan cau » toan cao, toan ban, toan tap

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 ((hien tach) OR (chiet tach)) - canh tranh cua ((tong cong) OR (dung cong)) phap toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hien tach) OR (chiet tach)) - canh tranh cua ((tong cong) or (dung cong)) phap toan cau~".
• Adding a wildcard symbol may retrieve word variants: hoc ((hien tach) OR (chiet tach)) - canh tranh cua ((tong cong) or (dung cong)) phap toan cau*.