Perhaps you should try some spelling variations:
canh giac » anh giao, canh tac
doanh bac » doanh bat, doanh ban, doanh bao
danh tac » canh tac, doanh tai, danh thuc
danh bac » danh bat, dan bac, dang bac
danh gia » dan gian
hien nam » phien nam, hien nay, vien nam
da hoc » dai hoc, dan hoc, day hoc

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: "((((\"danh tac da hoc viet nam\") or (\"((danh bac) OR (doanh bac)) da hoc viet nam\"))) or (\"((canh giac) OR (danh gia)) da hoc hien nam\"))".
• The words AND, OR and NOT may confuse the search; try adding quotes: "\"((((\\"danh tac da hoc viet nam\\") or (\\"((danh bac) OR (doanh bac)) da hoc viet nam\\"))) or (\\"((canh giac) or (danh gia)) da hoc hien nam\\"))\"".
• Removing quotes may allow a broader search: (((( danh tac da hoc viet nam ) or ( ((danh bac) OR (doanh bac)) da hoc viet nam ))) or ( ((canh giac) or (danh gia)) da hoc hien nam )).